Actually, the law you are referring to has been in existence since 1979 and it makes it illegal to modify a motor vehicle in any way that will bypass emissions.  This can include air filters, mufflers, etc. that alter the vehicle's performance and ultimately its emissions.  The fine is a maximum of $10,000 per day.

My understanding is that the "new law" is really nothing more than a renewed promise by the EPA to start enforcing the old law.

Whether or not it will amount to anything is questionable.  I live in a region that does not do emissions checks.  If your state/country does then who knows what will happen.

I think states like California may crack down a little more but ultimately I believe it will remain the status quo.  Especially for motorcycles.