I would imagine they won't play in Oakland for a few years before leaving like the Raiders did. Probably best to get away ASAP.
I am looking at A's attendance. They were a dynasty in the 70's and didn't draw well. They never drew 3 million fans in a large market area. I think the support has been a bit overstated. Otherwise, they don't lose the Raiders twice and A's.
A large number of the A's attendance comes from out of town and places like San Jose. Even back when I went to games with my grandfather in the 70's-2000's it was like that. I think they ended up with somewhere between 2-3 million attendance per season at their high point.
I remember the tail end of the Seals and the truth is the Bay Area just didn't 'get' hockey. While I'm not a Sharks fan, I do have to say that I'm glad the NHL waited until a time it could work and then found a place in the Bay where it would.
Oakland is very much a basketball town. The Warriors could be the worst team period and they were for long stretches and they had no problem selling out what became Oracle.
The Raiders have a very strong presence in Oakland and even today you can't wear certain jerseys in certain parts of Oakland. Ask my brother, who is not a sports fan whatsover, what happened when he wore a Bucs jersey because he 'liked how it looked'.... in Deep East Oakland. It was hilarious how many cars honked and dudes yelled 'TAKE THAT FKIN S#IT OFF!!'. It really could have been worse. But the Raiders always had a strong Oakland fanbase who tailgated with the best of them.