I believe the best way forward with cannabis will be to make it so that federally it isn't enforced at all but it is enforced at the state level.
Rescheduling it any other way at the federal level sets a precedent for all states. Kicking it back to the states (like abortion) allows each state to do what they want with it.
Conservative states can keep it illegal and the lefty states can legalize it. Or whatever the individual states decides to do with it
I recently had the thought that if a person living in a legal state gets busted by the Fed's for possession, a good defense would be the State was guilty of "Aiding and Abetting" . They allowed the person to break a Federal law. LoL