I don't think Elvis was "too far gone" at the time of the Aloha special.
During Elvis' career many false choices were made, and in 1973 The Colonel (and Elvis) made another mistake by not trying to do a world tour.
After the satellite show it would have been the right time to start a world tour and it would have been a tremendous hit!!!
On the other hand, you should put it all in perspective. Nowadays it's a normal thing for a performer (any performer or band) to make a world tour.
Back in the Seventies it wasn't.
Yes, Elvis could've had another first in musical history I guess...