The San Diego (for now) Chargers and Oakland (for now) Raiders have issued a joint statement about a proposed shared stadium in Carson, CA. There are several bullet points addressing various issues, but the meat of it is this:
"We are pursuing this stadium option in Carson for one straightforward reason: If we cannot find a permanent solution in our home markets, we have no alternative but to preserve other options to guarantee the future economic viability of our franchises."
Basically, what they're telling their home markets is that if they don't get a sweetheart stadium deal, they're prepared to leave. That means if Oakland and San Diego don't open the coffers, their current tenants are prepared to privately finance in Carson.
The franchises also made it a point to stress that they've worked directly with NFL Commissioner Roger Goodell on this and to remind everyone (but mostly Stan Kroenke) of the 3/4 vote required by teams to move a franchise.
This isn't a done deal by any stretch, but the race to Los Angeles appears to be on and Chargers and Raiders look like they are in the lead for the moment.