Within days of the San Diego Chargers announcing they will move to Los Angeles and play their games there next fall … someone has put forward the sort of free-thinking, out-of-the-box idea that might have saved the club for San Diego.

Granted, this $1 billion plan is built around a hypothetical Major League Soccer team, rather than an NFL franchise, but it shows the sort of multi-prong approach that might have led to the Chargers remaining in what had been their home city for 55 years.

It certainly brings to mind the old saying about closing the barn door … after the horse has already vacated the premises.

The key aspect of the plan from FS Investors is to build a 20,000-to-30,000-capacity soccer stadium, in which San Diego State’s football team could play, without using public money.

Taxpayers in San Diego were unwilling to put up public money to build a new stadium for the Chargers, and after demonstrating that for more than a decade the Chargers picked up and moved to Los Angeles, where a $2.6 billion project, including a football palace, is being built in Inglewood for the Los Angeles Rams — and now the Los Angeles Chargers, too.

The plan entails a $200 million MLS stadium as part of a $1 billion investment into the sprawling site centered on Qualcomm Stadium — which would be torn down for a batch of investment.

The plans for that would include acreage on which an NFL-size stadium could be built.

We know that “plans” is a very long way from “reality”, but the final days of the Chargers in San Diego seemed to show absolutely no creativity from all the parties involved.

Then, the week after the Chargers are gone … this wide-ranging plan.

It is not cliche to note that many cities in the U.S. do not move on providing competitive facilities for elite sports franchises — and the NFL remains on that list, while MLS does not — until after the big-league team is gone.

Some San Diego fans about now may be wondering why their city went down the same path.