I think the discussion about standard of living is quite interesting, because I agree that we take our rather phenomenal standard of living for granted. As a nation, we've pretty much nailed the part about what we need to live, and now our focus is on living well.
Standard of living is just one measure of ascendancy or decline, though it's an important one. I've read some stuff in the past about whether each generation is doing better than their parents, and some of the recent stuff puts the modern generation behind their parents in measures like home ownership and debt. I'll acknowledge that, but it also seems like homes are larger and toys are better and all sorts of other things are better. It would be hard to convince me that we're not still ascending as a society in that respect, with no particular crest in sight.
A key will be to not screw it up. How much of our ascendancy is the result of big deficit spending that's going to blow up at some point? How much of it is a fluke of the World War II destruction of other industrialized nations? How much of it is ingrained in the American system of government and economy?
My ancestors fought cave bears so I could make this post.