Surely it would be another excuse for the central gimmick, starring two modern actors eager to mimic one another.

Frankly that's better as a series of comedy sketches. Turn 'doing a Face/Off' into a recurring bit, like for SNL short films. Two-scene before-and-after pairings of actors with something to say about each others' careers. Occasionally involving Nicolas Cage anyway, because apparently he's still broke.