All very sound logic and entirely true for the present
However...
You are being extremely pragmatic and only extrapolating all of these factors into the future as if all of them are static and unchanging.
-America's economy WILL ALWAYS be based on what it is based on now. (No possibility that some unseen discovery or invention by the US could once again propel the US to an economic explosion of ridiculous wealth?)
-America WILL NEVER AGAIN have Robber Barons who wish to build monuments to themselves. (No possibility that some man will come along who's ego is almost as large as his pocketbook?)
-There will ALWAYS be a 2000 foot limit imposed by the FAA. (Rules and regulations will never again be able to be amended in the US? What you have now you will always have for eternity?)
Some of these "wishful thinkers" on here, used to be called dreamers and they were the ones that founded and designed a great America. Not the pragmatists. They were the ones left to figure out how to get it done. They didn't get to run things unless the economy was bad. (As it is now) And that is why your argument seems to make sense in these times.