This is the key bit from the embedded screen shot.
And the Senior Assistant Special Counsel in charge of this prosecution is a long time, career prosecutor with the internal authority to conduct this prosecution, separate and aside from his role in the Special Counsel’s office.
This is about the Manafort prosecution, but the takeaway is that the career FBI / DOJ people can carry on investigating whatever Mueller has already discovered, even if Mueller’s position goes away. That is, if Mueller’s team finds evidence of crimes, those investigations can continue without Mueller.
It is too late for Trump to fire Mueller. He’s doomed.