The failure of Prop 22 will cause a massive disruption of an existing marketplace. No matter what you think of the morality of the existing setup, the failure of Prop 22 will force some large structural changes to how it operates.
It seems likely that this will cause ride-sharing not to be economically feasible in rural areas where per-driver utilization is low.
Operating in SF and LA will likely remain profitable but many drivers will be forced, by AB5, to stop driving. This will increase wait times and increase prices and cause lower ridership.
It's very possible that Uber/Lyft will decide that the overhead of being an employer is not worth the reduced revenue, it's not like they're making a lot of money in the first place. It's also possible they'll decide they won't want to dilute their brands by offering a service which makes you wait 7 minutes for a ride.
It is, of course, also possible that they'll decide to send a message / throw a tantrum, but your comment implies this is the only explanation. It's definitely not the only possible explanation and I'm not even sure it will be the most likely explaination.