In the long term, "self-defense" is a poor choice of justification for the right to bear arms. Technology will eclipse firearms in that area and the foundation of such a justification will fail. While self-defense shouldn't be neglected, arms-bearing rights ultimately must be seen as something which it is improper for the government to interfere with simply because it serves none of the proper purposes of a government of a free people. For gun rights to be protected, the law must not understood as the government permitting certain things that have been justified for some reason. Instead, it must be seen as restricting the government from interfering with the people where the government has not been permitted. US society has strayed far, very far, from that principle.
I've mentioned this before, and I continue to anticipate a need for pre-emption of property rights on public accommodations. More and more of our society's public accommodations (transportation including streets and conveyances, housing, workplaces, markets, and entertainment venues) are becoming corporate-owned properties. At the moment, arms bearing continues on those properties mostly because detection is impractical. In the long term, we have to anticipate the right of trespass with a firearm can and will be denied. In some states, posted signs have the force of law to deny carry, but in all states the property owner can deny trespass to those who carry.
We're seeing a preview of this with Youtube, Facebook etc. Should those corporate properties be allowed to restrict speech based on firearms content? They are able now and many people side with their property rights over rights of free speech which don't apply to Google's property. But when corporations own the transportation networks and every destination on them, will those property rights continue to overrule the people's other rights? The SCOTUS has ruled otherwise with regard to the 1st Amendment (in Marsh vs. Alabama), asserting that free-speech rights were more important than property rights in a traditional public forum (the sidewalk) within a company-owned town. We don't yet have a similar ruling regarding defacto public forums like Youtube and Facebook, nor do we have a ruling with respect to 2nd Amendment rights on such properties.
The issue of property rights vs. gun rights is not a simple one. Property rights are sacred and cherished in the US. Most of us see it as proper that we control both guns and speech on our property. But most of us don't control properties that are also public accommodations like streets, sidewalks, parks, railways, and street cars. Personally, I wish the future was one where public accommodations remained public, but there is a preponderance of evidence they won't.
Another concern might be corporate gun-control by boycott pressure. We've seen this issue come up recently with financiers colluding to deny services to gun manufacturers. A deregulated firearms industry would not be vulnerable, but one that is highly regulated consequently needs protections. It's almost like nuclear energy, where the regulation is so restrictive, projects need loan guarantees because of regulatory risks. While regulations of firearms makers are not that stifling, they are enough to leave them vulnerable to finance and insurance boycotts. Anti-boycott laws like the Israel Anti-Boycott Act can be very problematic though. There are questions about whether this infringes on free-speech rights, and if there were anti-boycott protection for the firearms maker, one would have to question whether it's like forcing the banker to "bake the cake" against the convictions of their conscience.