Actually this talk is nonsense. The next move is to register all firearms. It'll happen eventually. Maybe not for another 20 years. But it's coming. FBI will find out who's hiding their firearms thanks to surveillance technology.
FBI could not find ALL US firearms in a hundred years!
Basic versions are stupid simple to make from common materials.
Ask the ghost of Nicolae Ceaușescu how the citizenry cobbled together sufficient arms to overthrow his regime despite his governments “Gun Control”.
In the frontier days a gunsmith could begin his trade in a new town with not much more than a file, hand drill, and raw materials.
Now we have 3D printers and cordless power tools.
They probably know already.
Do you think that fancy, super-secret X37B was just collecting data on foreign governments?
“The next move is to register all firearms.”
One billion (Canadian) dollars later, Canada has deemed its long-gun registration a total waste.