Gamers aren't going to care much about whether or not a monopoly is involved. They just want good games (at a reasonable price).
My take on the matter is that Microsoft is looking to use the scarity as a status symbol. Real gamers will have forked up the dough and will be able to use the game as a bragging right. Considering how some people back up Microsoft no matter what (irregardless of whether or not they're a gamer) and considering that speculators will be out in force looking for the 'hot' christmas gift in short supply, Microsoft should do very, very well for themselves.
I dislike Microsoft's business strategies, but they are VERY smart at business. (Ol' Bill sucks as a programmer though!)