This really makes no sense. LA has had trouble supporting one franchise. There isn't enough support for 2. Which ever team has more success over the next few years will emerge as team A will get the bulk of the ads and fans the other will whither and be forced to move.
I agree based on recent history: the Rams were fine in LA until the Raiders moved into town in the 1980s, then attendances dropped so much they packed up for St Louis. While LA has enough of a population to support two teams, back then it didn't have enough die hard football fans to do it come rain or shine, success or hard times - have things changed enough for that to happen now?
Out of curiousity, anyone know what kind of fanbase/attendances the old AFL LA Chargers averaged in 1960/61 before moving to San Diego?