First off- This would make no financial sense. Numbers time- FFXIII sold 1.8 million PS3 units in japan alone. To cut out that audience, SE would lose 108 million dollars. lets cut out the price of disc and packaging and all that stuff- I have no clue how much that is. But, for the sake of argument- Lets assume that it's 30 dollars(correction would be nice). For buying out the game to make sense, *just for japan, for the launch sales*, MS would have to pay around 60 million dollars. *FOR JAPAN. AT LAUNCH.*
(yes, I was too lazy for keep looking to world launch statistics, but I think even just japan makes a decent point.)
And as for the console discussion- The only two gaming systems you need are a PC and a PS3. Why? Most of the good (IMO) "360 exclusives" that you should care about are just not available on PS3. Mass effect, Left 4 Dead, . And PC gets a lot of decent exclusives of it's own. Plus mods. And free DLC, sometimes.Plus, you get to use mouse + keyboard. Which makes just about any game better.
As for the PS3, that's for buying console exclusives like FFXIII, MGS4, Rock Band, Little Big Planet, or games that had the injustice of getting a horrid PC port- pre-patch GTA4, Dead Space, Assassin's Creed, and a few others I can't think of of the top of my head.
Sure, 360 gets Halo, GoW, Fable, Dead rising, and a few other games, but it also has online that you have to pay for and an 70$+ wireless router. (and both Natal and Move are stupid, but Sony seems more aware that Move is stupid. Not many points for that, but still.)