Ahh, I believe the last time they performed the song was during the Leaders tour, because I have a San Francisco performance from '06 with it on the tracklisting. But he is quite right on the fact that he really can't sing it the way it sounds on AITB on it anymore. In the SF performance, he just barely hits the high notes, but he
can hit the notes at around 3:40 of the studio version.
But re: the high notes in Weather to Fly and Powder Blue, Weather to Fly starts off with a high note and never returns back to it, so it's easier for him to perform it than a song that constantly shifts like Powder Blue.
The only two AITB tracks that have survived over the years have been Red & Newborn. And I would be surprised that with the new material, some new oldies would be coming back.
But with the stadium gigs, there is no guessing as to what sort of set list they'll come up with for their return.