There has always been a hierarchy among elders. Now it's been validated by Kenneth Flodin in this talk about the word "princes". So not any elder can be a prince in the new order. Oh no, you have to be a governing body helper, or a district overseer etc. Have a look at 3:30 if you don't want to listen to the whole thing.
http://tv.jw.org/#en/video/VODProgramsEvents/pub-jwbmw_201603_1_VIDEO