I agree, buying/teaming up with level 5 exclusively would be the smartest move they could make this gen, that and of course the godfarther of Metal Gear! although mr. Kojima already has a strong partnership with sony so... 
I would say Square Enix, but lately they've been pulling a fast one left and right so...atleast Mr. Tetsuya Nomura is still Sony bound so maybe one day SE will get with it.
And lastly i really wouldnt mind if sony bought out a small percent of capcom, not for exclusive games but rather for Exclusive downloadable content from the PSN if you get my drift... *cough* RE5 *cough* :D








