Yup, CA Senators are basically life time gigs. Feinstein is just following the same ruts in the road Boxer left.
The Senators know that with The Bay and LA there is zero percent chance a Republican can take it and as long as they keep their donors happy, they figure they're impossible to primary and the reality is right now they're probably right.
It's kind of why I support the run at Pelosi's seat. I don't exactly love Buttar, but having one of the OGs lose, or at least barely hold her seat, would probably do wonders to refocus various incumbents on what their constituents want.