1) Both teams play in the oldest stadiums in the entire NFL. Oakland Coliseum was built in 1966. San Diego's stadium in 1967.
2) Al Davis coached both teams at some point in his career. In fact, if it was not for the LA Chargers, Al Davis would never have had an opportunity to become involved in the Oakland AFL franchise at all.
3) Both teams desperately need a new stadium built and are unlikely to get funding to do so.
The key difference in point number 3 is Chargers owner, Dean Spanos, could fund a new stadium if he wanted to but he won't.
The numbers simply do not add up in favor of a new stadium being built in Oakland or anywhere in the Bay Area. A new stadium is estimated to be in the 800 million to 1 billion range. Public taxes are not a solution. In the case of Oakland, the City, the County and the Raiders franchise are collectively STILL at least 100 million in the hole for stadium renovations made when the Raiders returned from LA.
The Raiders also suffer from a severe lack of corporate interest and sponsorship. You fill a lot of premium seating with corporate interest. The Raiders are simply not an attractive business investment for a number of reasons.
Like the demise of Al Davis himself, it is a slow burn for the Oakland Raiders franchise.
Mark Davis has offered to pony up 300 million into the project. That is quite a hefty figure but it will not be enough even if the NFL kicks in another 200 million as they seem to do for other NFL franchise stadium projects. The hitch is the City of Oakland, County of Alameda have no such financing available to pick up their end nor can they get close to anything resembling it. Nor would they allocate that money towards professional sports even if they had it to give. The reality is law enforcement needs that money if it ever materializes. Oakland is continually battered by idiots rioting and protesting, destroying their neighborhoods and local businesses when they are not busy robbing and murdering.
Look around you, the economics are impossible and no one with deep pockets cares enough about the Raiders to bail them out. There will be no new stadium in Oakland because it is a losing venture. That is the reality.
If you want to compare the Raiders to the 49ers situation, the 49ers have generated more than $400 million from the purchase of seat licenses for their $1.3 billion, 68,500-seat stadium in Santa Clara. Do you really think the Raiders can equal that figure in seat licenses? They can't. Remember that experiment backfired when they moved back from LA.
Now, the only real option for the Raiders is to move back to SoCal. That is if:
a) A stadium even gets built there. A SoCal stadium is not a done deal. Farmer's Field is still just a vision. The location near Dodgers Stadium is even further from a reality. Not to say a stadium in SoCal won't happen. Anything is possible but as of now, nothing is happening.
c) Would the NFL allow the Raiders to re-locate? It's not up to the franchise. Remember, Al Davis left an even more bitter legacy when he shoved his middle finger in the face of the NFL by moving to LA and then suing the league for 1 billion (then Al's lawsuit was laughed at and thrown out of court). There's an old saying, don't shit where you eat. Al thought he was above it all and genuinely believed he could beat whatever odds he faced to make the Raiders great. Just about all of his beliefs turned out to be untrue and now his son Mark is operating at a disadvantage to salvage the Raiders integrity and the franchise itself.
My feeling is the NFL league office is going to watch as the Raiders get backed into a corner they can't get out of and then force Mark Davis to sell. Roger Goodell the statesman is very good at blowing smoke but the larger plan he has in mind is to let the Raiders flap in the wind. The league owes the Raiders nothing and just because they are a team with lots of history does not mean they have a leg to stand on. They are one of the lowest valued teams in the NFL financially.
Unless a super savior emerges to fund a new stadium where the old one currently exists or the City of Oakland and County of Alameda pulls a rabbit out of their ass, the best outcome would be the Chargers and Raiders sharing a stadium in SoCal. Stranger things have happened.