I know I'm bumping an older thread but I just have to say this was well written and I am in total agreement with OP. I've had the same thoughts, Linux is great and my preferred OS but I will dual boot into Windows because AAA games and anything requiring DX11 is a no go. I absolutely do not like the idea of all games being tied to Microsoft's API forever, giving a single entity direct control and influence over the gaming market.
Yet I haven't made any effort to buy games on Linux. It's catch 22, if we're all waiting like OP said and nobody moves over, then developers have no incentive to develop games in parallel with Windows. If you care about being able to game on an OS besides Windows, you have to make the move and sacrifice a bit to make it happen. I fully believe Vulkan can be the future if we support it and vote with our wallets. This thread inspired me to make a more conscious effort to purchase games on Linux if they're available and use wine for DX9 offerings.
I fear for the direction Microsoft is going with UWP and Windows 10/Xbox integration. I have no reason not to believe Microsoft wants to corner the PC gaming market and control it. I could totally be wrong and Windows store is just another place to buy games, but their past tells me to expect otherwise.
In then end, Steam (and soon to be GOG) numbers matter, so the more we use Steam on linux and games in general, it will most certainly help but if we all sit here waiting for Linux gaming to happen, it never will.