Only complacency on the voters part will let him back in. That is why the GOP spends so much of its time on voter suppression, when the small margins in a few target states count, the anti-Trump vote must put in the effort.
It is what the right relied on here in the UK with the Brexit vote. So many believed it was a foregone conclusion and stayed home, in the end it was only about 140,000 votes that swung it.
Don't fall for it again.