Schedule 1 -> banned from the financial system.
Schedule 3 -> OK to use the financial system.
How the DEA schedule and the financial system interact is still unclear. The important part is that once regulations are updated weed businesses won't be restricted from access to the financial system. There may be some more regs around that access, but I'm sure they'll be worked around.
You already answered this already :)
> the point is that you CANNOT legally sell schedule 1 drugs commercially
Schedule 1 means illegal under (nearly) any circumstance, commercial dispensaries fall under “any circumstance.” Drug scheduling is just a tiered system for classification in order to determine which rules to apply to its sale, distribution, and possession of the substance.