I could see why it might happen:
1. Capcom doesn't have the healthiest finances
2. THey have had recent sucess on the 360
But:
1. Capcom, financially and creatively, has been on an upswing these past years and are showing no signs of slowing down.
2. They have been making efforts these past years to have a buisiness model more akin to a western development studio.
Meaning designing games to be cross platform and using a modular engine for all of their titles (developed in house though). They have vocally said that they will be maximizing cross platform efforts going forward.
3. I just think that there is too much potential revenue and mindshare available to Capcom as a free third party then there is for them as a Microsoft Games Studio subsidiary. True, titles like Lost Planet and Dead Rising will/have done well on the 360, but I don't think the 360 audience is diverse enough for all of Capcoms properties to do well. Both Deadrising and Lost Planet were titles specifically designed for the 360 userbase (as said by Keji Inafune), and to be honest the 360 userbase can have a narrow comfort zone when it comes to the types of titles they might gravitate towards.
I'm not convinced that Capcom would be willing to ultimatly sacrifice a good chunk of their properties when they can instead make games for the global market on all platforms. And target their smaller properties on the systems where it would make sense, while still being able to reach a wider audience with their bigger properties.
In other news Viva Piniata bombed: Selling 42 thousand copies on the 360. Viva is a good example of a title that would have done better on the Wii. Rare doesn't have the option pf picking the ideal platform for their projects, and neither will Capcom if they accepted a buyout from any of the big three.
There's probably much more profit to be made by producing awesome games that sell well, and entrenching the companies assets in each of the consoles and handhelds. That way they can target different properties at different demographics and counter milk each of the Hardware manufacturers with the possibility of ports to a rival system and timed exclusives for big payouts.
Not to mention that having a company with as many teams as Capcom would make no sense in an exclusive environment, so you'd see 'trimming of fat' and teams being merged or liquidated. Capcom would probably be against handing over the reigns of power to Microsoft Games Studios especially if it results in the managing of of their own operations being taken away from them.
. I don't know about know with the sixaxis since it now has a trigger, so it would feel really weird.
