The UN treaty would do nothing to gun ownership in the US. Unless you are getting your guns from an illegal source in which case you are not following the law anyway. The NRA uses this as a fundraiser but it has no basis in reality. Tin foil hat stuff.
There will be a push for gun control but nothing will pass its political suicide for to many politicians on both sides. All that the anti's have accomplished is to sell a heck of a lot of guns, ammo and magazines making tons of money for the gun companies.