More and more games run natively under Linux.
More and more applications can be run online or have non-MS sources.
Sooner or later, one of the many flavours of Linux will be an option everyone can choose to use.
You can compile and run UE Server, Game, Client and the Editor natively in Linux.
The only thing you can’t do is cross-compile content for Windows, but you could always use a virtual machine for that.
So, aside from DX12, why do we run Windows?