mmx: Some people aren't gonna be buying X-Box, but rather another system. Ever heard of the old saying "Don't put all your eggs in one basket?". Sega needs money now, and they're gonna make as many games for as many systems as they can sell.
That said, I don't see them doing much. I love my Dreamcast but all the really good games were made by 3rd parties, not Sega themselves. Sega's gonna die . . .