Don't freak out. Just a year ago, there was a bill to shut down the whole internet...supposedly. How do get Google, Wikipedia and over other good website to shut down for a day to protest not being able to get yellow tangs and some angelfish? Wait until it passes to worry. Then, wait until it gets signed.
In my lifetime, I have yet to see 500, or so, stop the momentum of 330 million. Just like the criminals can still launder money and find guns to use illegally (despite laws that only the otherwise good intentioned people will follow - I hate the new banking laws the most), somebody will find a way to get fish into the US if the demand is high enough. I am not saying to smuggle fish, since that would be hard (and smelly), but all that it takes is one stay order from any judge at any level that has a differing opinion of states rights from the USA that you can convince that a purple tang is not "likely to cause harm," and importing will begin again and more and more judges will issue that same stay. If this bill is truly to:"To establish an improved regulatory process for injurious wildlife to prevent the introduction and establishment in the United States of nonnative wildlife and wild animal pathogens and parasites that are likely to cause harm," then we have nothing to worry about. The only question that you have to ask is "the saltwater hobby has been importing since the 1950, and probably before, and what harm has it likely caused?"