Have to understand the 2nd Amendment isn’t just for you and me, it’s for everyone, regardless of persuasion. Only exceptions should be felons and mentally ill.
In such a society, a far greater emphasis would be placed on discerning and treating the mentally ill. I’d even bring back the institutions provided involuntary commission can’t occur without the 5th Amendment mandate for due process.
All that said, even in the Wild West when anyone could and did own guns, there were gun free areas back then. Usually this was a courthouse or a saloon. On rare occasions this extended to larger areas. So I’m not against gun free zones per se, but everyone needs to understand that these areas are favorite targets of mass shooters so the proprietors of said areas are going to have to be held responsible if they let in people with guns who shouldn’t have them there. The Dayton shooter being killed by police in less than a minute is an exception to the usual several minutes minimum that other shooters had to do their damage.