You'd have the spartan Byrne Krypton, Cat Grant, Matrix, the chubby "Kingpin" Lex, the elderly Ma and Pa, etc. You could even toss in some post-Byrne continuity with the Cleric, The Eradicator and Steel. I agree, this could be a fun story if handled right.
As long as the Pre-crisis version is still out there somewhere and isn't written out of history, as long as the Byrne or 90's version are not trolled out as the only true versions, I think it could work.
According to the current comics, this appears to be true.
That's a good thing, IMHO.