"Millions now living will never die" was from Rutherford's speech at the 1922 convention, if memory serves. I think it was modified to "may never die" at some point in order to soften the impact, though they also decided to forget Rutherford's predictions regarding the return of the 'worthies' in 1925, which would presumably precipitate the end. When that is taken into account, you can understand why he was so confident in his 1922 claim.
Then he got it wrong, and most of it was either forgotten or modified (and then forgotten).