Overall, almonds and grapes are cash crops - not food crops.
I'd bet a lot of unused almond and wheat meal goes to animal feed which is far less efficient than either of the inputs.
So the end effect or almonds vs another crop is diminished anyway.
The pulp that's left after pressing is getting fed to livestock.
The current model of farming in California is ultimately doomed; much of the groundwater depleted over the past century cannot be replenished as the ground has subsided and compacted itself after the water was pumped out. Basically the entire Central Valley sank by about 16 feet between 1920-1970 (https://www.usgs.gov/centers/land-subsidence-in-california/s...). Data since then is spotty because we basically stopped monitoring it.