It is easy for me to imagine them doing it, if they wait enough time, that most new hardware has no XP drivers anymore, and most programs/games depend on higher versions of windows APIs, the general public will not care about the then obsolete XP, just like they do not care about DOS, or Windows 3.11 and so on.

I agree that this is an act of kindness, that can not be depended on and it is entirely under MS control when/if it will happen.