I think you are right. If the economy continues to improve under Trump, he will be elected in 2020, no question. The stock market is up, and unemployment down, since he took office, and these things are far more important than the political correctness we might have got from a diplomatic President like Obama or Clinton. Trump will say things that outrage people, offend their sensibilities and upset foreign rulers, but none of that matters if he appears in four years to have delivered on his promises, and people feel that they are better off.
Rudeness is excused as blunt, forthright honesty, and people will say “At least we know what he really thinks!” We never had that from the last 4 Presidents or so; everything was planned, orchestrated and smoothed to the point where they delivered inoffensive, platitude-laden speeches which said nothing much of substance. Some would say we needed a regular guy, a straight shooter, a forthright talker whom we can at least understand, even if we don’t always agree with him!