Nothing to panic about yet, but there's a very good chance that massage is going to become much more regulated in California between now and the end of the year. What it's going to mean for this hobby is anybody's guess. My guess is that MPs will still be around, but you won't have a concentration of "hot spots" in certain cities like you do now. We will find out in coming months what's going to happen, and then it we will see how it plays out.
Basically in a nutshell, California is one of the few states where massage isn't a licensed practice. It has a "voluntary certification" here. Certain cities require all massage therapists working within their city limits to have that certification. Some cities do not. Some cities require at least one certified therapist on staff and the rest can be non-certified. Some cities don't require certification at all and regulate massage locally (either through business licensing or through the local police department). It's all over the place. This is precisely why you have some cities like Stanton and Westminster that are full of MPs and some cities like Irvine where there are none to be found.
The massage therapy bill that is currently in effect was due to sunset last year. The sunset got postponed to this year because of Covid, but the hearings are due to start up very soon to discuss how to move forward. Most of the industry is in favor of increased regulation, the reason being it isn't fair for a legit massage establishment operating in a "clean" city that requires 100% certification when customers can drive 5 minutes down the road to another city that has looser requirements and therefore cheaper rates. The public doesn't know that the cheaper rates are because they're getting an unlicensed and likely much lesser trained therapist. What is likely to happen is state certification will become mandatory for anyone practicing massage anywhere in the state, regardless of what city they're operating in. So those places in Stanton, Westminster, Orange et al won't be able to skirt the rules any longer.
Will this spell the end of MP's? Probably not. Cities like Downey for example. I went on a ridealong with a Downey cop back in the day when I lived up there. He actually pointed out all of the MPs in town (there were 6 at the time and most are still there 20 years later) and told me they know exactly what goes on in there. They choose to just monitor and mostly leave them be. If they bust them, what happens in there just scatters to elsewhere, so as long as it's in there and contained and not getting neighbor complaints it's not hurting anything. I suspect that's mostly how it will play out. But some cities may go a step further and rescind business licenses unless every single provider gets the state certification. For example, Stanton, or Orange, or Westminster may choose to "play by the rules" and close all of the MPs down.
On a higher scale it could become a state-administered license, which would be even more restrictive. Most people don't want that though. It just makes the process more bureaucratic and expensive for everyone. A mandatory certification would for the most part satisfy what the industry insiders want.
Bottom line: Be grateful for what you have available to you right now, as there very likely will be noticeable changes coming before the end of the year.