I think class three should remain available.

To ride a moped (legally defined, a moped is 50cc or less and no more than 30mph on a flat surface), all you need is a standard driver's license.

For a bike that goes below that, I don't see an issue with even an unlicensed person, provided they are driving safely.

I suppose the standard should be a certification or something similar to an ATV/Snowmobile certificate?