Though I do agree that the democrats are being overdramatic. In his first term Trump already was mostly just a puppet who just wanted to feel powerful and let other powerful people make all the actual decisions. Now that will be even more so as he's exhausted and mentally impaired. Trump won't be a dictator, he will be a puppet. The real power will lie with the 3 groups that put him there: The religious right, foreign dictators and the megacorps.
Hitler was in a similar condition but he was able to grab absolute power and dominate those, Putin did a very similar thing. I don't think Trump will though, he will just let the powerful interests do whatever they want no matter at what cost.