I think it will come down to a few things and this is all just my hunches. First of all is what the NFL views as serving its future interests. Other than that, I would say that St Louis is ahead of any other current NFL city in their plans to build. If they keep it going like they have, I think the Rams stay. If the Rams stay, the Hollywood Park project reverts to the original plan with no stadium. The Carson project is possibly fatally flawed and may be something the NFL rejects outright rather than putting the #2 market in a facility on top of a dump, next to a huge compost pile a stones throw from refinery row. This in turn leaves Oakland and SD in play and gives them more time. End result - LA still has no team and the three current markets figure out a way to make it work.
I think it would suck for LA but like it or not, LA has been there - done that and would likely be the easiest to move on from.