I believe at first 1914 was predicted to be the very end of Armageddon.. The very end of human rule on the earth, to be replaced by heavenly rule. This was held for some years after walrus sell died in 1916. Rutherford claimed that "the kingdom is now already 9 years old." (Paraphrasing)
This does not matter to Dubs, nor does doctrine. The GB could come it and say, "we made it all up! None of this is true, god is fake. Haha!" And there would still be an impressive number that stay, maybe even start a splinter group.
You Are right though, it is no exaggeration to say that the WT and all involved have a 100% success rate... Of failure