1. The re-scheduling will happen (90%), the administrative hurdles will be cleared. Only counterexample I could find was Kratom in 2016, which was the reverse of this situation, and the DEA dropped the proposal at the public comment stage.
2. Trump will not reverse it if elected (80%). He's been pro-states-rights on cannabis (or outright legalization) going all the way back 1990, and has criticized Biden on this.
3. Unlikely many US states that outlaw it will change, but I do predict (75%) at least one major European country will follow suit within a year, given Germany beat US to the punch
4. Effects in the US will be minor, outside of weed stores using the banking system as another comment pointed out, since most enforcement is state level.
5. But if there are changes, the best evidence we have on this comes from state legalization, where the effects are estimated to be huge (+3% state income, +17% substance use disorders).