Right now, Gartner are putting linux at less than 2% market share on the Desktop.
It is *much* higher if Android is taken into account.
I run windows for one purpose and one purpose only, the reader can figure that one out. But I think the big problem is not porting the games to the platform, it is the ancillary software that goes along with it. Track IR, ShadowPlay for the video casters, teamspeak (yes I know TS has a linux client, so does mumble for that matter, but the experience with them on linux is not as seamless as it is on Windows), joystick drivers and so on.
Similarly to Dash above, I suspect that Linux ports of most games will be dependent on a standard, consistent platform to deliver them on, because that is what is missing right now.
Right now, there are way too many potential linux platforms that are derivatives of another, that is in turn a derivative of yet another platform, trying to code for such a moving target in the kernel would be nothing short of Lovecraftian horror for the devs.
For those that might care a shortlist of issues would be:
Which framebuffer to target? Kernel Frame Buffer / X11 / Wayland / Mir!?
Which GFX target? OpenGL / DriectX via WINE or similar?
Which toolkit to target? QT / GTK / E / if they even went with a standard toolkit that is.
Which Platform to target Ubuntu derivatives / Canonical Ubuntu / Other Debian derivatives (Including SteamOS) / Debian / CentOS / Fedora / this list is huge
I would suggest to those that *really* want to see a Linux port to throw their hard earned expendable income behind SteamOS and start buying Linux games in droves on that platform, even the less well supported ones. To my mind, it is only by demonstrating that there is a market, that we can create a market.
Valve are aiming to standardize a platform for game production in the Linux space with SteamOS and that would be a good platform to target as a user community, because with a vocal community (that in this case spends cash) our influence over any game developer for a port improves.
I could easily offer more than 2p on this topic, but now I have to go and put my money where my mouth is and install SteamOS.....