Dude, Trump can fire anyone in government, including Mueller lol.
The question is would be expedient, *assuming* Trump is guilty. My point is that if Trump is guilty as the left claims he is, he's going to be impeached. Period.
If that's true, Trumps best play is to fire Mueller before he indicts anyone that could be tied to him, and hope that he can weather the storm until the economy improves or whatever. Impeachment is a political process and not a criminal process. If the economy is booming it will become politically problematic to get an impeachment passed in congress.
My own theory is that Mueller is in a conundrum. In the course of the investigation I think Mueller is finding dirt on Hillary and people in the Obama administration---perhaps even Obama himself. You have to consider that Mueller himself, could face indictment, if he uncovers criminal activity and fails to pursue it.
Don't be surprised if it takes an unexpected turn.