Pretty bogus premise. You don't "lose LA" forever by having a shitty or embarrassing year. While our season was both those things, the Rams are moving on, and people will move on. There's plenty of talent on the roster, and plenty of reason to expect a positive change with a new coaching staff.
It will take a while for football to grow back into the city again, and this would've been true even if the Rams had posted a winning record, or made the playoffs. True and lasting fans aren't won over in a season. Fans of the moment are, and they will be there any year your organization is doing well, and on an upswing. And when things start to turn, they'll find someone else to support. That's the way casual sports fans are, especially in today's social media culture.
When the Rams become winners, they will earn attendance. When they become consistent winners, they'll convert a portion of those fairweather attendees. For a while, they'll have to satisfy themselves with being a lot of peoples' "second team," or sideshow. Through the course of time, they'll be making an impression on kids, who are more likely than anyone to form strong allegiances at this point of their lives. It will be okay. There's no doomsday timer. It could take shorter, it could take longer, but there has been, still is, and will be a fanbase in this city. And if we hit a streak of winning seasons, that fanbase will blossom, and if we lose continually, the fanbase will wilt. It's what happens, it's not a special case like some folks seem to think LA must be. It's just franchises.
As for the Raiders, they've done a good job, like the Cowboys, forging and feeding a mystique. I'm not sure I'll ever understand the draw of those teams. In the Raiders' case, it certainly isn't their constant success. They've managed to cultivate an image and personality (or maybe just a color-scheme?) that lots of people identify with, and that's good for them. They're that team, and they're always going to have a following, because of the lingering mythos of an era where their identity meant something to people.
The over-the-top negativity is a bit much to stomach at this point. We know we had a bad season, but there's nothing to be gained by trashing a team where the talent is still high, our roster young and full of potential, and change is coming. If anything, we should be grateful that we're getting a clean break with Fisher earlier than we had cause to hope. Now is a time of looking ahead. The only reason this plash-guy's story deserves to be brought up is to be mocked.