While this is of course speculation, another team in California isn't out of the question. The LA Kings have recently seen some attendance growth, and expanding to the West Coast continues to spread the game across the U.S. to untraditional markets.
The Midway Rising development is a mixed-use residential, commercial, and recreational development which says will include a 16,000-seat arena. While this is by no means a huge amount for an NHL stadium, it is more than enough for an expansion team (and bigger than some current team's temporary home).
The biggest what-if that comes to mind for San Diego is whether or not the development will be completed on a similar timeline that the NHL wants to add another team. These developments can take decades to complete, and massive changes often happen throughout the process.