If she ran she'd make CA Gov. lean D, that's as far as a Republican can get it atm.
No she wouldn't, she'd do even worse than generic CA Republican.
I think she'd have a chance against a non-Newsom candidate.
The Republicans' main problem right now is Brown and Newsom are such strong candidates. Once they're out of the picture, the Republicans won't have held a statewide office for sixteen years.
The Republican's problem in California isn't that Brown and Newsom are strong candidates. I hate to give really simple reasoning, but it's literally because California is so Democratic and the Republican brand here is dead. Simply, there is no coalition that Republicans can put together to win statewide. The 2016 results show that the only places that vote Republican reliably anymore are places where no one lives. With a great economy, rapidly growing minority population (not that whites in California don't vote Democratic), a deep Democratic bench, a potential DvD race, and in a Trump midterm, Republicans will get wiped out in California in 2018.