Water is the primary limiter on city population sizes in the west. I wouldn’t be surprised if San Diego wasn’t at its limit already with respect to water resources, but I haven’t looked into it. Desalination could improve that.

If we could have Chinese work crews come in and build housing, especially 30 story concrete towers that are popular in Asia, we could build fairly cheaply, that isn’t really the limitation (it’s easier to solve than getting water to those new units for expanded population).