Sorry, edited original post. I think he will resign, he knows that If he waits, there is a good chance he would get another Premier League opportunity sooner. Possibly with a team closer to home. Someone like Brighton, Palace or maybe Fulham who could be back in the Premier League then.
Taking a relegated team straight back up is very difficult. When it has been done before, it is usually when the nucleus of the team that was relegated stays together. That is the complete opposite to what we expect to happen. How many of the current squad will stay if we go down?