I don't think it'll be as bad as it sounds.
I mean, I've seen photoshoped imgages of Mortal Kombatants and Street Fighter II character together and to my surprise, it looks pretty damn convincing. And besides! It's the 21st century baby!
So I say, BRING IT ON!!!
EDIT: In regards to the inevitable Vitua Fighters v's Tekken, well imho, that's a no brainer.
It's not a matter of if it'll happen, but the question is, WHEN?!
C'mon SEGA and Namco-Bandai!! Get off your butts and make this fight of the century come true/happen! 
29/07/2008
Melbourne, VIC - I currently own 108 Japanese (Region 2) SONY PLAYSTATION 3 BD games and 12 Australian (Region 4) SONY PLAYSTATION 3 BD games...TOTAL = 120