Well, Sessions has 9 toes already out the door, and once he's gone pot will have better odds of being rescheduled to a Schedule 2 drug.
Some think Sessions could be replaced by someone with even a more outdated view on pot, but I don't think so. Trump will want to run for another term, so he will want a more progressive person in that position.
Most Americans are pro MMJ and legalized pot. And if Trump wants their votes, a change needs to be made.