I think Trump is trying to get past the mid-terms. I think he’ll then use the congressional impeachment to can Rosenweasle and the Kebbler elf will leave of his own accord.
The senate will never convict, you have to have two-thirds and the democrats are not going to do this and you will find significant Republican cowardice as well.
If the Republicans retain the house and pick up senate seats either the theory of Session working behind the scenes and he begins reining hell down on the FBI/DOJ/CIA criminals with criminal indictments and prosecution or Sessions continues on as the James Buchanan of our time and Trump fires him and Rosenstien outright before 2020 or right after that election.
The current Republican senate has no belly for a new AG appointment and Trump will have to force them to fight if he fires Sessions.
Resign for reason of health issues.