Californian here. So far, my registration remains untouched. The county registrar's website provides an online form to opt out of mail in voting; however, I won't be filling it out because I'm thinking California will do it's typical "there was a glitch in the system" bs and use it to completely unregister me. And probably the day before the election. Also, when I go to vote in person, I'm taking my unused mail in ballot with me just in case the voter list shows I've already voted by mail. I might be overly optimistic, but because this vote by mail scam has gotten so much press, with even Trump talking about it, I think the Dems know that we the people are going to be hypervigilant this election, and it might just make them think twice about screwing around.