Once a team actually moves to LA all the other teams lose their way of threatening cities with a move to get a new stadium. What city is going shake their taxpayers for cash with the threat of the Portland Bills or the Portland Vikings (Portland, Oregon is the next largest metro area after LA without a team nearby)?
San Antonio, Portland, St. Louis if it loses the Rams, San Diego if it loses the Chargers. There's always another sucker somewhere.
There have been rumors that San Antonio would be in the mix for a team as well.
Within the US but you forget there are large markets outside the US that could be used for leverage. As well if an actual move is made that vacates at least one city. It is almost like a domino effect. In the case of cities that lost teams (Baltimore, Cleveland, St Louis) they quickly regained them. Well maybe Baltimore took a while. Anyway Toronto, Mexico City and even London England could be used for blackmail once LA is filled.