First and foremost whatever the case is, our Lord's response would nevertheless have to be the same in order to fulfill Scripture and give Israel every chance to trust in Him in accordance with God's sovereign plan. If Israel had accepted Him at that time it would have to have been prophesied and decreed which it was not. Then our Lord would still have to go to the cross to die for the sins of the whole world as prophesied to resolve the sin problem and then usher in the kingdom totally without the intercalation of the church age. Certainly in His Diety He knew of all things; and it is entirely reasonable for our Lord as Prophet to know this; for the prophets of old knew for example that Israel would not turn back to God but instead be captured by invading armies and even dispersed, yet they continued to warn Israel to turn back and even foretold that they would not repent and finally be dispersed for a long season. Our Lord prophesied of Jerusalem being sacked as a result of unfaithfulness which had to involve Him, their Messiah. Although Scripture has Him prophesy this after He was rejected, one might surmise that He knew of this all along:

[Mt 23:37-39]:

(v. 37) "O Jerusalem, Jerusalem, you who kill the prophets and stone those sent to you, how often I have longed to gather your children together, as a hen gathers her chicks under her wings, but you were not willing. 38 Look, your house is left to you desolate. 39 For I tell you, you will not see me again until you say, 'Blessed is he who comes in the name of the Lord.' "

And here is a prophecy that our Lord must have been familiar with especially since it is directly about Him which indicates that Israel will be responsible for piercing their Messiah and look upon the one they have pierced when He comes to the house of David and the inhabitants of Jerusalem with a spirit of grace and supplication and usher in His kingdom. Surely Jesus understood the meaning of this to be that He will be pierced for the transgressions of mankind at the hands of Israel:

[Isa 53:5]:

(v. 5) "But he was pierced for our transgressions, he was crushed for our iniquities; the punishment that brought us peace was upon him, and by his wounds we are healed."

And that was done at the hands of Israel herself:

[Zech 12:10-14]:

(v. 10) "And I will pour out on the house of David and the inhabitants of Jerusalem a spirit of grace and supplication. They will look on me, the one they have pierced, and they will mourn for him as one mourns for an only child, and grieve bitterly for him as one grieves for a firstborn son. 11 On that day the weeping in Jerusalem will be great, like the weeping of Hadad Rimmon in the plain of Megiddo. 12 The land will mourn, each clan by itself, with their wives by themselves: the clan of the house of David and their wives, the clan of the house of Nathan and their wives, 13 the clan of the house of Levi and their wives, the clan of Shimei and their wives, 14 and all the rest of the clans and their wives."

Furthermore, Mt 10:6 indicates that our Lord sent the disciples out to the lost sheep of the house of Israel:

[Mt 10:6-]:

(v. 6) "Go rather to the lost sheep of Israel. 7 As you go, preach this message: `The kingdom of heaven is near.' 8 Heal the sick, raise the dead, cleanse those who have leprosy, drive out demons. Freely you have received, freely give. 9 Do not take along any gold or silver or copper in your belts; 10 take no bag for the journey, or extra tunic, or sandals or a staff; for the worker is worth his keep. 11 Whatever town or village you enter, search for some worthy person there and stay at his house until you leave. 12 As you enter the home, give it your greeting. 13 If the home is deserving, let your peace rest on it; if it is not, let your peace return to you. 14 If anyone will not welcome you or listen to your words, shake the dust off your feet when you leave that home or town. 15 I tell you the truth, it will be more bearable for Sodom and Gomorrah on the day of judgment than for that town. 16 I am sending you out like sheep among wolves. Therefore be as shrewd as snakes and as innocent as doves.

[Later on in this passage our Lord prophesied that the message of repent for the Kingdom of God is at hand would be rejected by that same Israel]:

17 Be on your guard against men; they will hand you over to the local councils and flog you in their synagogues. 18 On my account you will be brought before governors and kings as witnesses to them and to the Gentiles. 19 But when they arrest you, do not worry about what to say or how to say it. At that time you will be given what to say, 20 for it will not be you speaking, but the Spirit of your Father speaking through you. 21 Brother will betray brother to death, and a father his child; children will rebel against their parents and have them put to death. 22 All men will hate you because of me, but he who stands firm to the end will be saved. 23 When you are persecuted in one place, flee to another. I tell you the truth, you will not finish going through the cities of Israel before the Son of Man comes. 24 A student is not above his teacher, nor a servant above his master. 25 It is enough for the student to be like his teacher, and the servant like his master. If the head of the house has been called Beelzebub, how much more the members of his household! 26 So do not be afraid of them. There is nothing concealed that will not be disclosed, or hidden that will not be made known. 27 What I tell you in the dark, speak in the daylight; what is whispered in your ear, proclaim from the roofs. 28 Do not be afraid of those who kill the body but cannot kill the soul. Rather, be afraid of the One who can destroy both soul and body in hell. 29 Are not two sparrows sold for a penny? Yet not one of them will fall to the ground apart from the will of your Father. 30 And even the very hairs of your head are all numbered. 31 So don't be afraid; you are worth more than many sparrows. 32 Whoever acknowledges me before men, I will also acknowledge him before my Father in heaven. 33 But whoever disowns me before men, I will disown him before my Father in heaven. 34 Do not suppose that I have come to bring peace to the earth. I did not come to bring peace, but a sword. 35 For I have come to turn " 'a man against his father, a daughter against her mother, a daughter-in-law against her mother-in-law-- 36 a man's enemies will be the members of his own household.' 37 Anyone who loves his father or mother more than me is not worthy of me; anyone who loves his son or daughter more than me is not worthy of me; 38 and anyone who does not take his cross and follow me is not worthy of me. 39 Whoever finds his life will lose it, and whoever loses his life for my sake will find it. 40 He who receives you receives me, and he who receives me receives the one who sent me. 41 Anyone who receives a prophet because he is a prophet will receive a prophet's reward, and anyone who receives a righteous man because he is a righteous man will receive a righteous man's reward. 42 And if anyone gives even a cup of cold water to one of these little ones because he is my disciple, I tell you the truth, he will certainly not lose his reward." 11:1 After Jesus had finished instructing his twelve disciples, he went on from there to teach and preach in the towns of Galilee. 11:2 When John heard in prison what Christ was doing, he sent his disciples 3 to ask him, "Are you the one who was to come, or should we expect someone else? 11:4 Jesus replied, "Go back and report to John what you hear and see: 5 The blind receive sight, the lame walk, those who have leprosy are cured, the deaf hear, the dead are raised, and the good news is preached to the poor. 6 Blessed is the man who does not fall away on account of me." 7 As John's disciples were leaving, Jesus began to speak to the crowd about John: "What did you go out into the desert to see? A reed swayed by the wind? 8 If not, what did you go out to see? A man dressed in fine clothes? No, those who wear fine clothes are in kings' palaces. 9 Then what did you go out to see? A prophet? Yes, I tell you, and more than a prophet. 10 This is the one about whom it is written: " 'I will send my messenger ahead of you, who will prepare your way before you.' 11 I tell you the truth: Among those born of women there has not risen anyone greater than John the Baptist; yet he who is least in the kingdom of heaven is greater than he. 12 From the days of John the Baptist until now, the kingdom of heaven has been forcefully advancing, and forceful men lay hold of it."

[Notice that our Lord's prognosis is not good re: His acceptance by all Israel so He can usher in His kingdom. ]

13 For all the Prophets and the Law prophesied until John. 14 And if you are willing to accept it, he is the Elijah who was to come. 15 He who has ears, let him hear. 11:16 "To what can I compare this generation? They are like children sitting in the marketplaces and calling out to others: 11:17 " 'We played the flute for you, and you did not dance; we sang a dirge, and you did not mourn.' 11:18 For John came neither eating nor drinking, and they say, 'He has a demon.' 19 The Son of Man came eating and drinking, and they say, 'Here is a glutton and a drunkard, a friend of tax collectors and "sinners." ' But wisdom is proved right by her actions." 11:20 Then Jesus began to denounce the cities in which most of his miracles had been performed, because they did not repent. 21 "Woe to you, Korazin! Woe to you, Bethsaida! If the miracles that were performed in you had been performed in Tyre and Sidon, they would have repented long ago in sackcloth and ashes. 22 But I tell you, it will be more bearable for Tyre and Sidon on the day of judgment than for you. 23 And you, Capernaum, will you be lifted up to the skies? No, you will go down to the depths. If the miracles that were performed in you had been performed in Sodom, it would have remained to this day. 24 But I tell you that it will be more bearable for Sodom on the day of judgment than for you." 25 At that time Jesus said, "I praise you, Father, Lord of heaven and earth, because you have hidden these things from the wise and learned, and revealed them to little children. 26 Yes, Father, for this was your good pleasure. 27 "All things have been committed to me by my Father. No one knows the Son except the Father, and no one knows the Father except the Son and those to whom the Son chooses to reveal him.

[Since Scripture supports that our Lord was very wise in His understanding of the OT Scriptures, especially the prophecies which predicted Israel's rejection of Him and acceptance at a time of His coming which was remarkably different from our Lord's First Advent, and their execution of Him, by His own people; it is not unreasonable to conclude that He did know of this prediction but as was His faithfulness to the Father's sovereign plan in His humanity He fulfilled every command and prophecy alike perfectly.]

Also, let's say the Jews would have accepted Jesus as their Messiah. What would have happened as the sequence of events? Would you and I be alive?

[It wouldn't matter as we would not exist if we were not in God's sovereign plan. Of course this could only happen if God had decreed it to happen, so to speculate on anying outside of what God has decreed is perhaps not as productive as to study Scripture to understand what He did decree. ]