No they don't "have to" follow a Cali law 13 years from now.....nobody does.
Technically what happened is that Virginia and other states actually passed state laws saying explicitly that they would follow the CARB motor vehicle emissions regulations by provision of “Section 117” of the Federal Clean Air Act. Basically they are complying with the Federal law by opting to piggyback the California CARB code instead of spending tons of money and research effort to come up with a different competing standard of their own, because lots of people aren’t happy with the EPA that isn’t taking action because of the political tug of war in DC
Sure there will be challenges in court, but because of how it’s set up, any state following the requirement is technically legally required to comply, unless they change their law back, which unless there’s a credible alternate standard (even the default EPA standard) will face considerable political opposition, especially since the major automakers have signed on to the deal
California has not actually explicitly banned combusition engines. What they did do is set a steadily increasing target requirement for the percentage of new car sales to be “Zero Emissions Vehicles” which culminates in a 100% number.
Far from as sensational as news outlets get, California’s definition of a “ZEV” includes not just Battery Electric Vehicles (BEV), but also explicitly includes both Hydrogen fuel cell (and possibly hydrogen combustion), and more critically, Plug-In Hybrid (PHEV) vehicles that can have, you guessed it, gasoline powered combustion engines. The definition of a PHEV includes some minimum required battery only range to qualify, which does mean that stop-start and mild and normal hybrids do not meet the cut.
It also looks like only some manufacturers (based on total sales volume) are allowed to count PHEVs towards the requirement.
Furthermore, it is a “credit” based system, meaning that at least until the requirement hits 100%, companies can elect to offset the requirement by buying credits from companies like Tesla that produce more than the required percent of sales. Presumably that means the credits will basically go away in 2035, but it also means PHEVs are still going to be around for some manufacturers that have smaller R&D budgets.
The specific language is:
BMW, Fiat Chrysler, Ford, General Motors, Honda, Hyundai, Kia, Mercedes, Nissan, Toyota, and Volkswagen must comply with the new requirements. Five smaller manufacturers (Jaguar Land Rover, Mitsubishi, Mazda, Subaru, and Volvo) are also required to comply with the ZEV requirements, but may meet their obligation with plug-in hybrids.
Of course the high level legal requirements, and how each state chooses to implement them can be drastically different. For example not every state requires that CARB EO’s be followed, and some states still have safety inspections where California doesn’t.