As I understand the proposed federal law, it would ban internal, non detachable magazines holding over 10 rounds except for .22's with tubular magazines. It would also ban semi-automatic shotguns and pump rifles and shotguns. An early report said it would also include lever action rifles, but that appears to have been dropped. The NY law apparently includes all of the above but sets a 7 round limit, with the explicit purpose of banning the M1 rifle, SKS, and Johnson, as well as dozens of rifles "capable of taking" a magazine over 7 rounds, and those magazines.
There was also talk in MD of including a handgun ban and just ignoring any state or federal court decision that went against them. Courts depend on the executive branch to enforce their decisions. At this time, it is possible that neither the president nor some governors would obey any pro-gun court order and no one would have the power to do anything about it.
Upholding the Constitution ultimately depends on the good faith of the executive who controls the police and armed services. If the executive acts in bad faith and chooses not to enforce the laws or court orders, or not to obey the constitution, there is nothing anyone can do, certainly not a disarmed populace.