A nice overview of where we might head now that the process has started:

https://www.politico.com/magazine/st...ed-next-215762

One not mentioned is the Trump Nuclear Option.
One version simply goes with Trump firing Mueller. He might not be able to that directly.Trump might be forced to fire his Deputy AG, and anyone beneath him who refuses to co-operate.
Upon finding a willing dance partner Trump appoints him/her to the vacant position using a law that allows temporary appointments (without confirmation) to fill a vacancy for 210 days.
The Total Destruction version hinges on something I have not been able to confirm. If the very position Mueller is in was created by an Executive Order, well that's just too easy. Abolish the post with a new Executive Order and the whole problem disappears!