In sunny San Diego, California there is a development group called Midway Rising that's aiming to build a state-of-the-art 16,000 seat arena. While San Diego doesn't give off the impression of a "hockey town" neither did Anaheim or Los Angeles or San Jose before the NHL built a fanbase there.
Over the last 5-6 years the NHL has expanded from 30 to 32 teams, bringing NHL hockey to Las Vegas and Seattle. The league clearly has an affinity for bringing hockey to warm climates and could continue that if they decide to expand to southern California once again.
Other potential expansion spots include Quebec City, Kansas City, Houston, and Atlanta.