If they did this, then the state of “California” would not exist anymore - right ? So does that leave us then with 49 states? Do these three “new” states get automatic acceptance to the “United States” ?
The new states would have to petition Congress for admission to the union and be approved by both houses. We will still have fifty states until both the state and federal authorities have okayed the change.
Presumably, the vote of the state legislature now would count as California's consenting to the creation of the new states, so the matter would move to Congress, in the unlikely event that California decides to split up.