About prospective debates: on the one hand, Trump's increasing mental deterioration makes it likely that his "advisors" will try to dissuade him from participating, no doubt arguing that he is too Great and Powerful to need to lower himself to arguing in person with a mere Democrat. That sort of flattery would be music to his inflated ego.
On the other hand, said ego would convince him he'd easily demolish any opponent, so he would certainly want to deploy his "best words" -- though they seem to be getting shorter and shorter lately. A nice question.
Of course, his team could insist on some new rules, perhaps something like this:https://youtu.be/WileufMiKMc