If it makes business sense for them, they should go for it. The Cowboys found someone willing to build them a billion dollar stadium. I'm not paying for it, so I don't care.
I think Sacramento would be a good move if they don't want to stay in San Francisco. They and the Raiders draw from Sacramento, and I bet they would also draw quite a bit from the Reno area.
Who knows. I was raised a Raider fan. :-)