Congratulations, you just required CDLs for almost every four door family sedan out there. The current Camry weighs more than that 3500lb limit. So'd the last Camry. The Honda Fit (aka, 'small city car'), which is about as small as you can practically go, is already over that limit.
My Pathfinder, which is actually a small SUV by modern standards, weighs more than your proposed limit. Oh, and all the classic car owners absolutely thank you for making it harder to keep their cars - you are aware that CDLs are much harder to get, much easier to lose, and cost one hell of a lot more, right? And your own truck is over the weight limit, so when will you be going to get your CDL now? And I hope you like getting random drug tests - they are mandated in some jurisdictions. And forget about going out for a single beer after work with your friends, because that can put you over the legal limit for a CDL holder.
Also, guess what, CF prices aren't likely to go down much more. In fact, it's likely to rise as increased demand will be related to the increasing cost of oil. Plus what happens when the government says, "Oh, yeah, starting from next year on, you're going to need to mount another 200lbs of safety equipment onto your car and too bad if it bumps you over the limit?"
This is a boneheaded idea. I'm all in favor of increasing licensing requirements, but this is ridiculous.