Definitely not. It means MS might make far less profit three years from now. They'll make far more profit now and in the interim period. In fact, right after a highly successful finished project would be the best time to rid yourself of a studio. They're hot property an you're probably not too invested in their next project. Add to that the rumors of 'developer strain' and it seems almost like a no-brainier.
Certainly there are some Bungie fans out there, but I'd venture to guess that the amount of Halo fans far surpasses that number. 'Guy at forum' might be critical, but he's in the minority and three years from now even he could have forgotten.
And as long as we're doing rumors and wild speculation. Who's to say that MS isn't eying up the next 'Bungie anno 1999' as we speak? Hell, for the money they must free up by loosing 'Bungie anno 2007' they probably could afford two or three of them and still have cash left over for coffee and danishes...