California must pay in full for all military bases and property belonging to the United States. They must also pay for relocation of all former US citizens who wish to resettle in the US. After doing that, they can go to hell.
There's more to it that that. What about all the U.S. veterans living in California? What about air traffic control. What about college conferences and sports leagues with members inside California?
We should offer Cali a payment plan to leave peacefully. They have to pay for the federal resources they acquired within 50 years' time. I'd encourage them to leave, frankly.