Almond production might move elsewhere. Don't underestimate how incredibly efficient personal water use is in California and the Southwest, and how much room there still is for improvement.
You should change the title to the Western US. This is a problem effecting neighboring states too, notably Utah (Great Salt Lake), Nevada, and Arizona (Colorado River). Long-term, also the Great Plains moving east from the 100th meridian (Ogallala Aquifer). And then we might as well talk about the impact of rising sea levels on the South's Gulf coast and Florida.
This is a nationwide problem. Better question: what's left for climate refugees to flee to? The Great Lakes and New England? Too bad there's no jobs and/or it's too expensive.
The agriculture industries in California (especially the more water-intensive ones) can gradually move to the Midwest and the South, bringing the jobs with them.
I am personally not really sure exactly how intensive climate migration will be, but I can say this: its not very simple nor practical for the crops being farmed in California to just be moved elsewhere.
The reason that California is used so heavily for farming crops such as avocados, almonds, walnuts, grapes, etc. is due to its dry-Mediterranean climate. California is, in fact, the only region where this climate type can be found in the entire country.
This makes the region highly conductive to the creation of massive farms that create much of the US' (and in the case of almonds, the world's) crop supply in certain foodstuffs. Simply put, you can't replicate these kinda farms in other regions of the US, just as you can't create cornfields in Washington nor a cotton plantation in Maine. If California is facing an intense climate crisis in the form of a drought, worse than we've ever seen, the answer from farmers is not to move out east, but to downsize their farms.
This isn't as simple as moving a factory from Michigan to North Carolina. With climate-related disasters getting worse in California, the long-term effect will be a massive strain on certain aspects of the food supply. It's pretty easy to see almond production get downscaled to such a degree where its simply too expensive for casual buyers.
