[zaarn]

No I won't.

Valve has been pushing for Linux support in case they need it as fallback (see: Proton, Steam Machines, etc.)

Atleast at Valve there is a certain amount of fear this might happen.

[PhasmaFelis]

It's certainly something they might do. It wouldn't be totally out of character for MS. But there's no evidence that they're "trying to push their own store and close down Windows gaming for themselves".