It was one of the most memorable parts for me, too, and I don't remember interpreting it that way.
I just pulled out my copy of 1984 to check the article's interpretation. Through most of the appendix, the tense is a bit ambiguous, but there's a line that seems to indicate Ingsoc didn't prevail in the book's world: "It was expected that Newspeak would have finally superseded Oldspeak (or Standard English, as we should call it) by about the year 2050."
I just pulled out my copy of 1984 to check the article's interpretation. Through most of the appendix, the tense is a bit ambiguous, but there's a line that seems to indicate Ingsoc didn't prevail in the book's world: "It was expected that Newspeak would have finally superseded Oldspeak (or Standard English, as we should call it) by about the year 2050."