As the article notes, this idea has been batted around for decades by conservative Californians who don't want to live in a liberal state. It's a fantasy with little chance of happening, but it always gets the politician who proposes it a little bit of ink.
Same for eastern Oregon joining Idaho
And all of “not Chicago” Illinois being part of Indiana
ECOTOPIA is back in play. (1975 novel, Walden-Twoish)