I am not a lawyer. I am a retired psychotherapist. However, I did watch all 456 episodes of the original Law and Order.
If Donald Trump decides to fire Jeff Sessions he will have to find a replacement either to replace him immediately as a temporary attorney general to thwart whatever emergency plan Robert Mueller has to issue a report and/or indictments in this eventually while Rod Rosenstein was still in charge. Trump would want to fire Sessions and appoint a temporary acting replacement at the same time.
Trump would have to find someone he absolutely trusts will do his bidding to not only stop the Mueller investigations but to make sure that the preliminary findings and planned indictments never see the light of day.
There is one major fly in this ointment besides Trump having to deal with public outcry and the likelihood that this action would be used in a Democratic House as another example of his criminality, that is, obstruction of justice.
The newly appointed acting AG would be able to see whatever evidence Mueller had gathered, quite possibly a tentative report prepared for such an eventuality. I think the facts would implicate members of Trump Incorporated up to and including the godfather, President Donald J. Trump.
Unless this person was absolutely corrupt, and I do not rule out this possibility, they would feel that to do their job responsibility they would have to read the report before they put it under permanent lock and key.
If he or she did so and saw compelling evidence that the president his various top associates had committed treason by conspiring with the Russians and each other, as well as other lesser crimes would they join in the conspiracy by covering up criminal activity they had no part of?
They would take the risk of eventually being implicated in Congressional inquiries.
Also, would they be so morally and ethically bankrupt they could live with themselves and face their family and friends?
It is difficult to believe that Trump wouldn’t know that he was the leader and intended beneficiary, however hands off he was in implementing the dirty details, of a criminal conspiracy that would lead to an execution in the public square of the capital city in many other countries.
Assuming the worst, If Trump actually believed that he was innocent of any wrongdoing, he would be psychotically in denial and certifiably delusional. He would have to be unmoored from reality to such an extent that I do not think he could function adequately in day-to-day activities.
Back to the new acting attorney general. Who could Trump find who was willing to engage in a cover-up that made Watergate conspirators look like a bunch of kids trying to clean up after a raucous house party before the parents came home?
Would Rudy Guiliani do it? He might turn to Fox News, so consider the following possible candidates. Would Jeanine Pirro do it? Would Alan Dershowitz do it? Would Greta Van Susteren do it? Would Ann Coulter (she’s a lawyer too) do it? I doubt any of these would take the job.
Among the lawyers, at least of those I’ve heard of, there’s only one I could think of who might take the job. That is Andrew Napolitano, the far-right conspiracy theorist who was repeatedly praised by President Trump and who was suspended from Fox News after his conspiracy theory that President Obama used UK spies to spy on candidate Trump was a major embarrassment.