Yeah, every few years someone else comes along, says the're gonna do it, and then it fizzles out.
Remember Cheryl Stearns?
http://www.cherylstearns.com/mission1.html
If I recall correctly, there was a Frenchman a few years back also.
The issue is almost always simple: money.
One of a kind pressure suits, one of a kind gondala/ballon, etc. Better come to the table with more than a few million dollars.