I really don't care too much. Haven't been impressed with Rare very often. The old SNES games were great, Banjo-Kazooie and GoldenEye and DKR were great, but for the last few years on N64 they really sucked. Banjo-Tooie sucked ass. JFG was very disapointing. DK64 was horrible. PD was unimpressive. Conker was funny, but as a platformer it wasn't great, and it lost its appeal fast. And I've never been interested in SFA.
So personally, I don't care that they're gone. But I will miss Donkey Kong Racing
Still, I think it's stupid that MS bought them. Then again, Xbox fans only buy thing because of hype, and the Rare name will fit right in. But Rare was good working with Nintendo, and everyone agrees Nintendo makes great games. Microsoft on the other hand, can't make a game to save their soul, so Rare loses the help and it stuck doing it on their own. Best of luck to them, but I'm not expecting the same stuff that we've seen before.