Did the Gospels predict that God would turn to the Gentiles and form the church from Jews and Gentiles?
No, the Gospels do not predict that God would turn to the Gentiles and call out a body of Christ from Jews and Gentiles. The Old Testament and Gospels contain no mention of the church age; they looked forward to Christ's suffering, death, resurrection, wrath, and the coming Kingdom.
Les explains that the Old Testament prophetic program had no room for the church age. The timeline ran from Abraham through Christ's first advent to Israel, His crucifixion, ascension, then the wrath of God in the tribulation, and finally the Kingdom. He notes there is not a word in the Old Testament about the church age, nor in the Gospels that God would turn to the Gentiles and call out a body of Christ of Jew and Gentile. Peter on Pentecost had no concept beyond that Old Testament timeline, saying what was happening was the fulfillment of prophecy.