Only thing really holding everything back is all the new multiplayer games require kernel access. Those are not compatible with Linux (with very very few devs making the effort for any changes). If we can get those studios to make a few changes it would really drive growth.
In order to get rid of them you need baby steps. And DX12 to Vulkan would be a big undertaking. Especially since half the Vulkan development is going into translation efforts from DX.