I remember seeing posts predict Legion and BFA here, a couple days before announcement. They weren't any of those silly, attention-seeking "my dad's uncle's friend's grandson works at Ninten- Blizzard and gave me all the lavish details of the latest xpack that take up 2 pages!" affairs but short and to the point description of the expansion's name, theme and major features buried in between two other posts. The Shadowlands name and theme was predicted by many but the actual expansion and its features weren't, not by any I saw anyway.