On another note, Norman Geisler points out that the Greek word for "generation" can also be translated as race. So Christ could be saying this Jewish race shall not pass away until the end of the world.
My Greek -> Dutch dictionary says indeed that γενεὰ could be translated by "race". However, that use is only attested with Homer, and only for use with animals. FYI, Homer is about the oldest Greek we have on record, approx. 800 years before the NT was written.
So, epic fail. Or is this latent antisemitism with Geisler, equating Jews with animals?