We're getting the next set of GC ranks in 3.4 along with a new tier of GC rewards and quests so to some extent your request is already in the works.

3.4 is apparently dropping quite a lot of additional GC content as well, including the ability to recruit and train your own squad to use for something. Details are still sparse but they clearly have big plans for the GCs going forward now, I think they were just waiting for the Heavensward arc to be over.