Arizona, Miami, Southern California and New Orleans are all in the mix as a part of the rotation due to their mild winter climates and local ammenities.
Miami has fallen out of contention primarily due to their aging facility. The voters their voted down renovating the stadium so Miami isn't expected to get another one without those renovations occurring. Dallas and Houston are going to be added into the mix and I expect the Bay area to get a couple over the next several years. Phoenix's biggest competition will be from Los Angeles if they get a team and San Diego if they renovate the stadium. Even then the Phoenix area should get one ever 8-10 years or so.