No need for any of the gun control crowd to worry. Pretty soon the new open relations with Cuba will make illegal automatic weapons more available and cheaper, especially in Florida.
With thousands and thousands of miles of coastland, with drones, with millions of shipping containers, it is not necessary for a terrorist organization to even blink if the USA imposes some kind of weapons ban.
Any foe with half a brain can figure out a way to get weapons into a country.
They managed EASILY in Paris.