"and the feds could ban guns
Under the power of ... what?
"the states could ban guns outright"
Some guns (if it's not against the state constitution), yes. Not all guns. If they banned all guns they couldn't have a well regulated Militia.
They may not be now, but by your interpretation - coupled with your incredible passion for insisting thereon - they could be.
Under the power of ... what?
Same power that lets the feds enact and enforce 922(o). You don't seem to have a problem there. Just remove the "machine" prefix from "machinegun" in that law, and they're pretty much gone (save some expensive bickering over "it's legal, you just have to pay an insane price for pre-'86 ones").
Not all guns.
Why not? As you noted: "the California State Constitution does not protect the RKBA". Same goes for a bunch of other states. For those that do protect RKBA in their state constitutions, you've made it very clear that's a choice up to the majority (supermajority, whatever applies) of voting citizens in those states.
I've been following your posts for a long time. From what you have written (by the volumes), you advocate (with extreme prolific passion) an interpretation of RKBA and the 2nd Amendment whereby individual ownership of arms can, in all practicality, be outlawed (save for some legalistic saving trivial technicality, such as, say: militia members only consist of Irish-descended midgets, and they're only allowed muskets while on patrol for the UN in Nigeria).