In the context of the original discussion, Jesus' use of the "near" demonstrative pronoun aute (this) would clearly indicate that the "generation" was something tangible at the time his disciples framed their question. This would have been well before any of various facets of "the sign" were manifest, and not at some future date when "the sign" in its entirety was visible.
Personally, I think the whole idea of "types" and "antitypes," "primary fulfillments" and "secondary fulfillments" is a bit of a stretch to begin with, and borders on the ridiculous when the expositor is free to deviate from the prior pattern and rearrange things to suit his or her eschatological views.