I can't see the Glazers, or RATcliffe handing over the sort of control Emery would want. They'd want to meddle.
And I also think he's happy at the Villa.
They seem to hand complete control over to whichever bloke they most recently thought was a good idea, hence the likes of Brailsford, Ashworth, Berrada and (inexplicably) Wilcox having loads of power at one point or another before they move on to the next one.
Obviously Ratcliffe is a complete moron, but at some point they are going to probably going to accidentally make good choices rather than bad ones. And it's not impossible that thinking of Emery, and then agreeing with Emery that he should be in charge of things rather that bloke who was alright on the wing for Blackburn twenty years ago could be a chain of events that happens.
I still think that by the far the most likely scenario is that Emery starts next season as our manager. But Man Utd are probably one of the *very* few risks that he doesn't.