Actually, it's the Lukan context which convinces me that either Yeshua wasn't. or that He was engaging in a play-on-words. As you've pointed out, Luke 21 distinctly speaks of the destruction of Jerusalem in 70 AD which began "the times of the Gentiles." It then leaps forward to the Second Coming. It would be impossible for the same generation to witness both before passing away.
I'm speaking of his use of the entire future section as if He were present at the time.