While I agree with most if not all of the reasons you list for the growth of Mac gaming, I think you’re omitting one fairly big one: Microsoft itself basically broke the Windows gaming market into pieces.

I say this as someone who, for a number of years, kept a Windows machine with reasonable hardware specs around largely for gaming, alongside his Linux boxen. I really couldn’t do so any longer after the release of Vista. Learning that Microsoft had removed its support for hardware-accelerated 3-D audio made me feel like a bit of a chump while sitting amidst my 7.1 speakers. My choice was basically to either “upgrade” to an OS that was significantly less game-friendly both in terms of features and raw speed, or cling to an OS whose lifespan was far from known, given that its progenitor frequently and loudly proclaimed its determination to shoot it in the head just as soon as it wouldn’t piss customers off too much. I chose Door Number 3 instead, and decided to part company with Windows gaming entirely. It hurt, but less than I’d feared.

Maybe the whole thing was some kind of back-handed attempt to drive Xbox 360 sales; if so, it hasn’t worked in my case.

It would be nice if Microsoft decided to rebuild, with its next Windows release, some of the bridges it has recently burned. But I’m not holding my breath, and if you’re right, I may have moved well past caring by the time they actually get around to doing so. (The only game I see myself having to play, more because of a friendship with someone who’ll cheerfully Zerg-rush my base than the game itself, is StarCraft II, and Blizzard has already made it clear that the PC and Mac releases will be simultaneous. Awwyeah.)