Everyone would say that Bret would NEVER return to WWE. He ended up returning in January 2010 after 13 years!
The other one was that everyone said Rock would NEVER appear in WWE other than some small promo like the one he did for WM23 and that the one on SD . On Raw we all know what happened there, not only did he return, he cut a 10+ min promo in the ring without anyone(minus the gm) interrupting.
So the 2 moments that just over a year ago people would say it'd never happen ended up happening. Then a possibility of Sting going to WWE makes me wonder what other statements that are similar to what people said about Bret,Rock and even Sting could be said now?
Only ones I can think of are Macho Man and Ultimate Warrior returning and/or being inducted into the HOF, but that's about it.