I don't think Ubisoft is so much at risk.
They have diversified rather well this last few years with AC and Prince of Persia and their Montreal studio has been churning best sellers every year...( they lost the head of the Montreal Studio 2 years ago which was supposedly their pillar there and it didn't affect AC at all).
If I had to make a guess it would be Square Enix as it still isn't diversified that much out of Japan and despite the Wii success overthere the Japanese market overall is still in a slump....
Or any other big Japanese developers that make the majority of its revenue in Japan...
Overall development and marketing costs have increased and it's getting harder and harder to gets back on costs with just Japanese sales and quite a few Japanese games still don't export that well..( and the arcade market that a lot of Japanese companies use to supplement their revenue is doing really bad).
PS3-Xbox360 gap : 1.5 millions and going up in PS3 favor !
PS3-Wii gap : 20 millions and going down !
