20 years ago this would have been a valid argument. All OEMs are making Chromebooks now and those are easy to buy anywhere.
Good point... and yes it does seem like the "main stream" Linux that has the best shot of dethroning MS is Chomeos. Adding Linux support now... and soon enough I'm sure they will add 3D support and actual games. May not be a big AAA gaming push out of the gate... but it seems every year Google ups the hardware and software targets of their os.
The main hurdle was OEMs and that as you say isn't an issue. At the rate google does the +feature every year I would think in a few years AAA gaming on chromeos machines may not be all that crazy.