The guy is over 70 and he'd be commiting himself for at least 3 years (the very least). They have to move on from him sometime, they have the chance to do it now, not just postpone it for a couple of years. I'd say there is next to zero chance of it happenning. They need to appoint an A lister...
Why on earth would he go back as an also-ran in the league and reduce his reputation. As it is he went out as a champion with an over-achieving team. He must be loving it.