No, the 2nd amendment can't be nullified by executive order. That's alarmist. Such a think is unprecedented in US history. But what can happen is what happened in the UK. By the time of Dunblane, gun ownership had become rare, and rather anathematized. Once a few generations had grown up under the regime created by the Firearms Act of 1920, gun owners were more and more marginalized. Gun ownership was seen as more and more fringe. Wacko. Paranoid. The left is already struggling to achieve the same cultural shift here in how society views gun owners. If they succeed, they can drum up enough support to get the 2nd amendment repealed. Once that happens, kiss your guns goodbye.