I know the traditional view of elections is now up in the air because of 2016. Incumbency is still a good advantage, and if the economy continues to get better then that may be all is necessary for a shift back. Also it's not like the Dems can hit him any harder than in 2016 unless he does/says even more that is stupid, which is likely.
Incumbency is still a big benefit, but on the other hand, Trump only got 46.1% of the vote. He hasn't really gotten much more popular since then, so he's extremely vulnerable if a relatively scandal-free and somewhat energizing candidate can come along and pick up the voters who voted for Clinton and those who voted for neither. Trump hasn't tried to reach out to any other voters, including those who didn't vote for him. This really does hurt him in reelection if his image is still poor. Trump doesn't have to lose a single voter of his to lose 2020 handily, given how low his support was already.
Trump's position is really precarious. Not only can he not afford to lose any support, but he actually needs to be gaining it, and with his approvals the way they are, that isn't happening. He has also energized the opposition as well - something that they weren't in 2016.
Just my 2 cents, anyhow.
