It will be interesting to see whether Valve can encourage the move to Linux gaming. Their biggest asset at this time is the distribution model of Steam, but that's not sufficient to get the big publishers to develop for OSX, never mind Linux. Edit: Valve's game list: http://www.valvesoftware.com/games/
OS X is not a good platform for gaming. It has a significantly smaller user base of which only an even more significantly smaller are gamers. Playing on a MacBook (or at least on my MacBook) is impossible, and I wouldn't buy an iMac for gaming. On the other hand, you can put Linux on anything (for free!), from your mom's 2002 pc to the latest generation hot stuff. This means there is indeed a potential, and somebody…
The other things is about Wine, they're working on accelerating the Direct3D driver, and OMG, it's soooo fast now. I'm running Skyrim on a custom Wine engine (1.7.1 with a patch from the D3D boost branch), on hight/ultra settings on my Macbook Retina, It's running at 80% of the Windows performance. And it's only the beginning, it's far from done. I also have it running on a friend Macbook Air, it run at medium setting at a solid 30 FPS.
My point is that you can actually plays with Macbook nowadays.
Edit: The PR from codeweavers is relevant (Especially the part about the Command Stream). http://www.codeweavers.com/about/general/press/20131112/