Ferguson has clearly indicated he will stay on in some capacity and will have a lot of say in who replaces him. From all I've heard Ferguson say, I can't recall another manager, he is as complimentary of.
I've felt for a while that Moyes has to some degree, tried to replicate some of the things Ferguson has done at United. I wouldn't be surprised if Ferguson felt he could mould Moyes as his replacement.
I think it's a matter of time.