12 years is a lifetime for technology.

By the time 2035 rolls around, the mandate won't be needed, as the problem will have largely fixed itself.

The reason? Cost.

The initial purchase price of EVs are on a downward arc. The initial purchase price of internal combustion vehicles are on a slight upward arc. Those arcs will cross within the next two years, three at most. And when those lines cross, the market will speak, customers will rapidly abandon internal combustion.

And EVs won't just be cheaper than ICE, they will continue to drop in price. Consider that the drivetrain of an EV has about 1% of the components of an ICE vehicle's drivetrain. This greatly reduces the component cost, the assembly cost, and the costs to manage the production and acquisition of all those unneeded components.

Most of an EV's cost are with its batteries, and batteries on an even steeper downward price arc than EVs themselves. Currently, most major auto-makers are on a mad rush to build as much battery capacity as they can, as rapidly as they can.

The reason EVs are generally so expensive today is because the automaker's limited battery capacity is being dedicated to the vehicles with the highest margins, luxury vehicles. Battery capacity is rapidly increasing, and as it does, batteries will be allocated to the auto maker's full product lines.

The auto-makers know that internal combustion is dead, as most have already abandoned internal combustion R&D. Meaning, the best ICE vehicles that will ever be made will be released in the next few years. After that, no improvements, ever. And once those divisions are shuttered, there will be no going back. The knowledge base will be lost to time.

TLDR - Internal combustion consumer vehicles will largely be gone by 2035, irrespective of these laws. Customers vote with their wallets, and as battery production rises to meet demand, EVs will soon be absolutely cheaper. Cheaper to buy, and much, much cheaper to operate. Not just lower fuel costs, but far lower maintenance costs with far greater reliability.