There's been no change of administration at CARB. The changes in D.C. won't affect that. Also, the U.S. is no longer the world's biggest car market. Two reasons to think we won't see a rehash of the 90s.
Yes, CARB stands for the California Air Resources Board and the Democrats still run California. The states that have adopted CARB guidelines also tend to be dominated by Democrats.
Now there are the federal CAFE standards and the ICE makers are putting pressure on the new administration to weaken those. However, there is a new force outside of the regulatory structure that could make the CAFE standards irrelevant: the Model 3. If the Model 3 becomes the iPhone of cars, it will completely shift the focus of the entire car industry and whether the CAFE standards are scrapped or not it will be irrelevant.
The CAFE standards were a way to try and nudge the industry towards alternatives and better fuel economy in general, but the world is reaching the end of what can be done with ICE to make them more efficient. I ended up with a Model S because I wanted something with the same performance as my 1992 Buick with at least 20% better gas mileage and no ICE could do it. The best modern cars can do (for the same size class of car) is about 10% better gas mileage if performance is about the same. The way they get better mileage is make the cars gutless with 0-60 times over 10s.
The Model S's price is out of most people's price range and it was at the absolute ragged edge of what I could afford. For someone like me the Model 3 is a no brainer. Once people become educated about the advantages to electrics beyond the better energy efficiency, they car industry will be transformed forever and the gold rush will be on to build as many EVs as quickly as possible and Tesla will be 5 years ahead of everybody.
At that point, the CAFE standards will go out the window, they become irrelevant. Some car companies will fold and others will merge trying to stay afloat in a market that has changed and they have the wrong product. But the debate over CAFE standards will mostly be a quaint bit of history at that point.
It isn't guaranteed the Model 3 will be the game changer, but that's the way I'd bet today. The economy could tank in the next year or two, or Tesla could make some critical mistake that hurts them badly, but if things go even 80% according to plan, the Model 3 will be the crack that broke the dam.