Wouldn't you just immediately await futures for the most part? No need for it to even be stored. That said, I do agree that good design will enable possibilities outside of the original definition.
Just a nit: Cell doesn't really work with Deref, you can only really move into or out of a Cell, not take a reference to the insides (unless you have a &mut Cell<_>)
Also another reason why await field won't be that confusing is because most futures are anonomous either by async or impl Future so you couldn't access fields anyways, this should lead people to realize that something special is going on.