Something in St. Louis Rams fans' favor, working against the team's hypothetical future move back to L.A., is that the Rams could be pretty far back in line. Look at this list of teams whose stadium leases are due to expire soon:
2010 - Oakland, New Orleans
2011 - Minnesota
2012 - Buffalo
2014 - St. Louis
Besides the four teams soon to become the NFL franchise equivalent of unrestricted free agents, you've also got the Jagwires, Whiners and Chargers pretty actively looking to improve their stadium situations.
My prediction has been that L.A. will have two teams again by 2020, thinking Rams and Jagwires, but by the time the Rams are clear of the Dome lease, L.A. may not have room for them, with at least six other teams spoiling to move, excluding Buffalo, widely considered a lock to move to Toronto in the near future. The Rams may not even make San Antonio's short list, which I'd believe includes the Vikings and the Saints.
Where would the Rams move if L.A. and San Antonio's openings are filled? Not to any current NFL city; if those cities were, or became, attractive enough to draw the Rams, they'd keep their old teams. So where? Oklahoma City doesn't have the juice to steal another major sports franchise, do they? Memphis? Mexico City (Las Ovejas?) Speaking of "Las", would the NFL dare to move into the city built on what it considers its biggest taboo? (Would Al Davis give them a choice, if he lives long enough?)
AFC East: Patriots, Jets, Dolphins, Toronto
AFC North: unchanged
AFC South: Colts, Titans, Texans, L.A. Jagwires
AFC West: Chargers, Broncos, Chiefs, VEGAS Raiders
NFC East: unchanged
NFC North: Bears, Lions, Packers, San Antonio
NFC South: unchanged
NFC West: Seahawks, Big Dead, Whiners, L.A. Rams
At least the Rams will be staying in the country...