evidence for a prediction?
since you asked so nicely, i'll explain. trump's voting base was built on a rally against the uniparty. immigration, the economy for flyover states, and as a pushback against the increasingly neo-liberal US. did you see the crowdfund for his wall? there are groups of people in that voting base that are committed to his cult of personality. we aren't going to go back to the days of someone like mccain, jeb, rubio, etc as presidential candidates. people just won't take them seriously anymore. and when dems are running people like kamala (literally just black hilary), warren, booker, etc, who don't have the connection with your average person in the US(like bernie did, and tulsi does now), they lose their advantage against whoever the republican candidate would be, that will just follow trump's example of tapping into issues that rile people up.
wouldn't surprise me at this point. but all this depends on who runs in 2020.