Perhaps he is not done. Perhaps he is just retreating to regroup with his most trusted allies. He has no allies in DC - even Pence, probably the military brass wouldn't support him at this moment.
I am only guessing, but perhaps he, Flynn, Admiral Rogers, Grennell & others... maybe Bannon....have a plan.
Some have a theory that he has to step aside because military needs to deal with this... if that were the case Pompeo could possibly step into the role for now while all the fraud and foreign interference gets sorted out.
I remain hopeful for now. At least until tomorrow.