China will not be invading they’ll be invited in!
They don’t need to project anything.
Regardless, what kind of message will California succession and US meek acceptance say to the nations of the Pacific rim? The US will cease to be a Pacific power, Chinese Blue Water navy or not. For the US it would be a Trafalgar-like defeat without a shot being fired.
I just don’t buy this whole scenario. China has its own problems to deal with and is not in a position to project power all the way across the Pacific.