I'm not sure a more realistic scenario would sell any guns.
You just summed up a significant amount of the conversation around guns in the U.S.
That bad?
Jesus fuck, yeah.
And a lot of it feels like obsessive planning around how to handle one particular moment, without though of what happens after that moment (i.e., you have shot someone, how will now have to deal with the legal ramifications of having shot someone- WHETHER OR NOT IT WAS "SELF DEFENSE." And it will be hell for you EVEN IF YOU WIN YOUR CASE. Which you PROBABLY WON'T.)
At this point, the pro-gun defenses that make the most sense to me are preppers (it at least makes sense on its own logic) and people planning to suicide with the gun (also makes sense on its own logic, but that's not going to be widely argued on the 'pro' side anytime soon). Most other arguments just don't hold water for me.