I think it will be interesting to watch the nation implode if the damn SC rules against the individual RKBA; states like California and Massachusetts (among others) would surely try to enact a ban/confiscation on handguns. I don’t think any government, state or federal, has the resources nor the manpower to collect guns from the near 150 million citizen who have them.
They won't come for them all at once, but they will act swiftly where they can. Just a few more "reasonable" restrictions and registration, then keep them in the armory, then final confiscation. All the while they will make examples of those who don't comply. This will keep most people going along to get along.
By the time they start the confiscation most Americans will be worse than ignorant of gun culture and most of the guns will be locked up at the armory. Those who would cry "from my cold dead hands" at this time will only be too easily accommodated as they will be alone and ostracized.
America will be Land of the Free no longer. Sorry to sound like a pessimist but history tells this story, not me. If this decision goes the wrong way enabling the above scenario then a massive groundswell must start immediately. Otherwise you can say bye-bye to your guns and/or your life.
The folks that are left will ALL be criminals in the eyes of the state. Of those....3/4's will actually BE criminals...the others will be folks like you and I.
...or the b@lls, I expect.