Sorry to be late with a reply here. I have been working with 1,000+ others to fight this bill since just before Thanksgiving. I also fought it before it was signed into law, but at that time, they implied there would be more exempt professions than there are now.
It's unclear if S-Corp and/or LLC status is, on its own, sufficient to meet the 12-point B2B exemption as currently written, but at least some freelancers are working with employment attorneys to do things like incorporate as an LLC in Wyoming ahead of the January 1, 2020 AB5 implementation date, and then still pay California income tax as a resident.
If you're not already, please feel free to join the California Freelance Writers United group on Facebook (some members of which are part of the class-action lawsuit filed against AB5 by journalists), and Freelancers Against AB5. There are many coordinated efforts going on, from group meetings with lawmakers, to meetings with attorneys, to consultations with the law firms representing the existing class-action groups.