A lot of the discussions of how conservatives critical of Trump should or will vote in 2020 make the mistake of pretending the group is a monolith. There are actually several reasons different groups of conservatives opposed or were reluctant to support Trump in 2016.

Ex: For the conservatives who prioritized policy, Trump has been much better than expected in many areas.

For those who objected to Trump's character, he hasn't changed or adapted to the office.

For others, it was a balance of those things that they must now weigh.

Most importantly, circumstances have also changed. Democrats have moved significantly to the left since 2016, but their nominee doesn't have nearly the same likability issues as the nominee in 2016.

Point being that there are lots of factors that voters weigh individually.

Last point: I can respect most position except the people who pretend they are the principled opposition to Trump while openly abandoning all the principles they claimed to believe in to oppose him. No one should take those people seriously.