Different sets, NOT the same ones
The concept could come back but with different circunstances to get them, not in the form of a "timed challenge".
Maybe in a different format. Or not, maybe keep it as it is.
The question is if you think they should comeback in any way or form.
"Gear with Unique Animations that is impossible to get once the expansion ends"
Video of the Old Animations:
https://www.youtube.com/watch?v=_miwVnvK2Kk