...it's possible we'd see a world where the majority of US citizens vote to repeal the second amendment,

The people will never get a chance to vote on the amendment. You need overwhelming majorities in both houses to bring an amendment forward. Even after that, you need an overwhelming number of state legislatures to approve. With our divided society, that ain't happening, ever. A gun ban would never fly in any case. Guns have been part of the American psychology since day 1. They are part of the hunting culture. Part of the wild west, frontier mentality. A ban on assault rifles and gun restrictions is more feasible, but not an amendment because of the reasons already stated.

Given a choice to vote on gun restrictions, Americans would approve, according to the latest Gallup Poll.

Is the U.S. in a decline, socially, culturally, and economically? Possibly. Donald Trump's popularity may be a symptom. If we look at the rise of extremist leaders in the past (i.e., Mussolini, Hitler), these gained popular support during times of profound national stress.

As for the rest of your laundry list of our ills--be skeptical of what you see in media. Remember that news is filtered by the news reporter. We are a divided society in many ways. One way is our quality of life. I drive around, for miles, and see no drug addicts. See no poverty. Yet, if I wanted to, I could find a neighborhood not far away where these are common. Is this not true of the UK?

Homelessness, on the other hand, visits all communities. This is a conspicuous symptom of social and economic distress that seeps through everywhere, it seems. The homeless are not only among us. Increasingly, they are becoming us.

Well, no argument from me, @mobbs. Just more thoughts.