Trump has something like 85 or 90% support among Republicans. OK, I can knock that % down in my head a bit by saying that some of those numbers are people who are being 'good soldiers' for the Republican party, supporting him in poll responses.

But he still has that 35% or so, nationwide, presumably mostly Republicans, who never wavered in their Trump faith. Trump, even if he loses big, will not go quietly into that night. He'll still be blathering on Twitter, and endorsing candidates. And 35% of the entire populace is more than enough to win primaries that only involve 1/2 (or less) of the populace being in the voting pool. Trumpies will get out and vote in those primaries, so Trump's brand of Republicanism will continue to have an impact for awhile. 4 years? Maybe even after his death depending on who picks up that flag after him.