I think that this could end up true if the next Xbox really is "just a PC".

The PC gaming ecosystem is a powerful selling point, especially due to the existence of Steam, emulators, modding, etc.

Windows really needs more refinement and polish though, the current experience is mostly unacceptable for a living room PC.

A next-gen Steam Machine would likely be a better competitor to the PS6, it doesn't have the reputational baggage that Xbox and Microsoft currently has.