The price I would pay is less linked to how long I planned to live my own life and more based on how long I expected AA to live!
Logically .... if you put $3m in the bank at 5%, this would yield $150k per annum ($90k after 40% tax or, if you're a US resident, $150k after tax if old George does scrap tax on unearned income to help all those poor billionaires out there). $90k would buy you a LOT of First Class airline tickets and, of course, you'd still have the $3m in the bank. There is also no mention of what fare classes they would book you in.
Did you see the small print? Fill in the enquiry form and someone will get back to you within 2 business days. If I was considering spending $3m on a product I'd expect a bit more instant service!
And why are they so keen to tell you that you still get AA miles? You've already got unlimited AA travel for life! (Except, of course, for all the places AA don't fly - which is, erm, most of the planet.)