I’ve used Steam Workshop before and there’s no denying that it is very convenient and useful.
TBH, I can’t really see the MS team getting involved here on Steam. If anything were to happen like that then, if allowed, it would probably be a Steam and a Steam Community effort.I think that MS would, if anything, prefer a freeware download site as an accompaniment to their own payware Market Place site.
That said, a good idea and I could be wrong