Trump would have to be lobotomized to do something as astronomically stupid as firing the special prosecutor who was appointed specifically because he fired the director of the FBI. It is unfathomable, even given Trump's CV.
We are talking about the same Donald Trump right? The guy that not just fired the head of the FBI investigating his campaign, but went on NBC and essentially told America he did it to obstruct justice? Who get's his first daily briefings from Fox and Friends and his nightcap from his routine calls to Hannity?
......To be serious for a second, there comes a point where you back a dog into the corner and the only option left is to bite.
It was astronomically stupid for Nixon to go on a firing spree until he found someone willing to fire the special prosecutor. He did it anyways, because the other option was to allow an investigation increasingly closing in on him to continue. Nixon likely calculated it would be worse for him to allow the tapes to get into the prosecutors hands than taking the chance from the fallout from firing him.
Is there shit in those emails or in the subsequent interviews where they assumed Mueller did not have those emails that is incriminating enough to make the president or his team draw a similar cost/benefit calculus? IDK, I suspect no, but if there is something that gets the president past that threshold, and confident enough in their smear campaign, I think Trump has shown the capacity to go to great lengths for self-preservation.