Things are as good as they're going to get for Trump. He hasn't faced a real economic crisis and he's actively trying to start one. A recession or inflationary spiral between 2018 and 2020 would probably be enough to kill his chances for reelection.
I would have agreed with you unequivocally if it wasn't for the recent child migrant issue. This seems to finally be opening peoples' eyes somewhat. Let's just hope it lasts. Trump's peak was probably April-early June of this year. And even then, that's only when you judge his administration on the curve that it often finds itself on.
