Uber is not a profitable company with fat margins like Google, Facebook, Amazon, Apple or Netflix. I don't see any way for Uber to absorb the increased costs that come with full employment without reducing the number of drivers and increasing the cost of rides in California.
The change in employment classification means that drivers will no longer be able to choose when they work. Uber will choose when they work, and for how long. The barrier to becoming an Uber driver will increase. Currently, in most cities it's possible to sign up to drive entirely online and basically just requires a license and a completed background check. Going forward people who want to drive for Uber will have to interview like any other job, probably in-person with a resume, and jump through the many hoops which that process entails.
My guess is that for new drivers who can pass the interview and existing full-time drivers who don't get laid off this will bring a big improvement in quality of life and provide some much-needed financial security and benefits. The rest will be out of a job.
I think it's unfortunate that some kind of compromise couldn't be reached which would have provided some economic security for these workers while accounting for the real differences between gig work and regular employment.