It all started with Stake.com's "hyperactive" animated avatars and i bet it will end with their avatars too.
After the disabling of uploading animated avatars by Theymos, some campaign managers like Hhampuz even went ahead to encourage members to remove the animated avatars and stick with the static ones
Firstly, theymos clearly does not state that he will disable all animated avatars, especially avatars worn before the change. It means users who worn animated avatars before the change will be able to wear them as kind of glitch. But, if they change to another avatar, they won't have chance to wear another animated avatar again.
Secondly, changing from animated to static avatars due to the change totally depends on companies, not managers.
Hhampuz is a good manager, so he would contacted to companies to change all avatars from animated to static. It is just my theory.