[andrewjl]

California can do that, but the demand for fruits and veggies will still be there. California grows the vast majority (in the US) of quite a few of those: peaches, carrots, strawberries, and others.

Instead these will need to be shipped from overseas by marine transport which is an intense source of pollution.

[wmil]

California only ended up with the majority of those markets due to the how federal agriculture subsidies are structured.

You can grow carrots and strawberries almost anywhere in the US. Peaches need things a bit warmer, but again most of the US is fine.

It makes sense to shift water intensive crop production to states with water.

[btilly]

And it is little appreciated that federal agriculture subsidies are structured the way that they are because maintaining food security was seen as necessary for the stability of our country.

To see why you have to go back to the Dust Bowl, and then the prospect of severe famines in Europe at the end of WW II. It turns out that if you have 10% more food than people need, food is cheap. But make that 10% less and food becomes very expensive, people starve, and you get political unrest.