Really all that is needed to beat Trump in 2020 is simple: remind people that he's the establishment now. They
are living in Trump's America. There is no benefit of the doubt left to give the man, and all the shakeups we were promised aren't happening. I read one of Trump's recent speeches (a very bizarre one in Long Island, which forced the local police department to put out a statement clarifying that they do not condone of mistreatment of prisoners) where he has this curious description of coming in "like a movie" and "liberating towns" from gangs, "even here long island." That liberation being immigration services taking the immigrants away. If you buy that, that sounds great, but if you actually live in a "liberated" town and it doesn't feel so damn liberated, it makes everything else he says look like hot air. At some point people will want to be able to
see what Trump promised everyone.
If you do that they'll have the room to make a decent platform offering an alternative to what will be his various failures and how they would do better. 2018 will presumably be a dry run for that.
btw i'm really not joking, that's actually how he described it:
At another point, Mr. Trump painted a cinematic portrait of freeing a shackled United States. “One by one, we’re liberating our American towns,” Mr. Trump said of the work to remove undocumented immigrants.
“Can you believe that I’m saying that? I’m talking about liberating our towns. Like you’d see in a movie,” Mr. Trump continued. “They’re liberating the town. Like in the old Wild West, right? We’re liberating our towns. I never thought I’d be standing up here talking about liberating towns on Long Island where I grew up. But that’s what you’re doing.”