As predicted!

When they went after lawn mowers, ATV's, and other engines not used on roads, it was just a matter of time.

https://www.youtube.com/watch?v=qZ7ykSfY-t8

https://www.rvtravel.com/breaking-motorhome-market-crisis-california-rules-shutting-sales-6-states/

…..but wait! There’s more!! prospective RV owners are taking a hit!

This is a classic catch 22 proposition. If there aren't that many cars in the first place to offer much improvement, why bother?
The other argument us, if there aren't that many cars effected, what is the problem with implementing the restriction?

how would this affect classic/antique vehicles that use regular plates ?

I think the issue here is with antique plates is they are openly self-identifying, and in states that restrict their cars use, by destination or mileage, that opens the door for a traffic stop to inquire if the car's use is according to restrictions.
No reduced cost antique plates, no restrictions.

That video is a year old. Those survey's did not result in anyone losing their old Mopar.