Ron Whitten postulates the upcoming PGA at AAC and its new and excellent bermuda greens might open up both US Open and PGA sites to the far south again. Yeah, it will be hot, but at least the new turfs can take it without life support systems.
Personally, I don't think it can be a US Open if it doesn't get around to all feasible parts of the country regularly. In some ways, while there would be a lot of one time infrastructure costs for the courses involved, that big picture thinking might even trump architecture as a selection criteria. Hey, if need be, you can change the architecture a lot easier thay you can move, say, Houston, TX.