I'll go out on a limb here. Just my view, but typically, most Americans don't get so involved in politics that they storm the capital. Most don't even get involved to the point they buy a hat, t shirt, put flags on their pickup trucks. MOST just go to work, watch an ocassional news story, have an idea of which party they will vote for and go on with their lives. Which is one reason the "Look how many people showed up to Trumps rallies verses Bidens rallies" didn't hold water with me. Almost all the people I know personally ,voted, I don't know anyone who attended a rally, but they were worked up enough to make sure they voted. So I suspect Trumps supporters are more vocal, more outspoken and more visible than Desantes supporters, but I think by the primarires, Desantes will beat Trump. I never respond to calls from politcal pollsters. I suspect most normal people don't. Trumpsters do... and it may give a false picture. Just my opinion
The Trump rallies definitely measured voter enthusiasm in 2016, which was directly related to voter turnout. They were massive. So I disagree that his rallies were not at least partly predictive of the outcome.
The only thing that changed in 2020 was Covid.
I'm not seeing a scenario where DeSantis beats Trump. We've already seen the establishment get behind a candidate (Jeb Bush) and Trump killed him. DeSantis is no Jeb Bush, but I don't think the big money getting behind DeSantis will lead to a different outcome. Trump's support in the GOP is just too strong.
I went through a running analysis of the numbers in 2016 showing that the majority of GOP voters did not support Trump during the primaries, and he still won.
There are a lot of talking heads trying to speak it into existence, but I will believe it when I see it.