Donald Trump could win a second term.
Donald Trump's base is solid. It will not respond to reason, science, or facts. It is a composite of cultists, white supremacists, white evangelicals, and Republican politicians. This constituency is not large enough to win the general election. It can, however, win the needed 270 votes in the Electoral College if the pro-Biden/anti-Trump voters don't vote.
I believe, the majority of voters have already made up their minds. For those sitting on the fence, consider Trump, the president, only exists because there was a base waiting for someone like him to give voice to their fears and concerns.