I don't see this happening. There are too many other bigger environmental issues to tackle first. Perhaps CARB will declare a rule at some point that will apply to CA, but I don't see it being implemented federally. When I think about the volume of diesel emissions, it's 1) older or non-compliant OTR trucks, 2) people with modern vehicles but DPF deletes, 3) antique vehicle owners are a distant third due to the reasons listed above.