I am confident that the composition of the court will change, during my lifetime. I suspect yours as well.
FWIW, I do have a strong opinion on school shootings, of course. I am not comfortable with the assertion that there's something uniquely broken about Americans that means we can't have RTKBA. But if there is, I'm not confident that eliminating 2A would resolve the real problem.
Why not? The age of the justices in order from oldest to youngest is 75, 73, 69, 68, 63, 58, 56, 53, 51.
Even if you're 60 or older you have a pretty good chance of seeing the composition change.
Of the remaining five members, it takes only two conservatives to ensure that the court remains that way. Assuming that future nominations are equally distributed, there's about a 2/3 chance that at least two will be conservative.
And let's just say that I don't think it will be randomly distributed. The existing court composition has a thumb on the scale of future nominees. The party that nominates conservative judges has won only one election outright this century, but until recently only one opposing candidate had been able to win -- including once because the Supreme Court directly stepped in.
It's harder to calculate just what that means, but I think it's sufficient to affirm that the odds are very long against being able to generally reverse this court's direction before Halley's Comet returns.
It doesn't matter whether it's "justified". The Constitution means what five people on the Court say it means. And if that comes from talking to James Madison on the ouija board, the rest of us have to live with it.
In that sense, it's "settled". And our daily school shootings are just a fact that we have to accept.