The Chargers have a pretty big following in Orange County and North SD County, I think they will still be able to draw pretty well in Carson, and that's not even considering any IE fans.
The bigger issue for the Chargers whether they play in San Diego, Carson or Timbuktu is the inept ownership, management and coaching. I have never once thrown in the towel on supporting a team, but the way they treated Weddle was pathetic and now retaining this clown as coach just makes it tough to have any kind of optimism about the franchise. And I love Rivers as a player, but Rivers isn't good enough right now and hasn't accomplished enough in his career to be dictating who coaches the team, he loves McCoy and apparently went to bat for him, just as he did to buy Norv an extra year.