I have been looking at your question for quite some time, and i decided to check the most resourceful sources. But i don't really have the right answer for you.
But what my honest opinion is, unless the developers of World of Warcraft announces it, i can't either.
Well, i would guess that in every expansion, they would eventually remove the stuff that would be easy to obtain, so that the people that actually did it before in the older expansion actually had something to brag about. But then again, they didn't remove Undying and Immortal. So you actually have a small chance...
Yet, only time will tell.
