That's why I advocate pressure being brought to bear for Trump to step down as the 2020 nominee, before the primary season begins. There is nothing that would frustrate the Dems more, because without the Trump punching bag, they've got nothing.
Okay, if we could magically flip a switch and have Nikki Haley be our 2020 nominee, great. While we're at it, we could just ask Trump to grow to the size of a Titan, wade on over to North Korea, and pluck out their nukes and missiles with a wave of his mighty meat hooks.
But I think both are equally unlikely. I mean, didn't you acknowledge many months back that there was basically zero chance of him quitting on his own, or of any other Republican beating him? Given your criticisms of Trump, I really can't imagine that you see him as someone who would truly be willing to walk away just because some in the GOP asked him to. If anything, the louder the calls on him to resign, the more likely he is to flip everyone the proverbial bird. That's pretty much the core of who he is.
If there's one thing the election of 2016 accomplished, it was to convince Trump to not believe the polls, and that there really is a mass of Americans who may lie to the pollsters, but will come out for him on Election Day.