What could have happened if Israel as a whole had accepted Jesus?

Les teaches that if every Jew had responded to this message, the King could have returned. Of course, they had to have the Tribulation first, and then the Kingdom could have been set up, and Israel could have evangelized the world. Les calls it a great opportunity that they miffed and rejected. Instead, God converted another Jew, Saul of Tarsus, saved him by grace outside the land of Palestine on Gentile ground, took him down into the desert for three years, and seminary trained him between the glorified Lord and old Saul himself, and then sent him not to the Jew but to the Gentile with a whole new program.