Nixon resigned, and as you stated in a previous post, you don't think Trump will ever do that and I agree with you. Trump will burn Washington down and the US for that matter, before he ever walks away from the presidency. I think the only way he will leave office is in handcuffs. I believe even if he loses the 2020 election he will contest the election results even if it was a landslide.
I think constitutional crisis is on the horizon for the nation, now Trumps lawyers are telling him not to be interviewed with Mueller. This is going to be messy.