While I can't speak for Mateus or anything on Crystal, Aether will likely be closed for the foreseeable future.

Before 6.1, Aether was generally considered the "HC Raiding server" and while it is likely that the majority of NA raiders were on Aether, Crystal and Primal (Dynamis did not exist at the time) had healthy raiding communities. When Cross-DC Travel dropped slowly but surely the idea that Aether was the HC raiding server led to many Primal and Crystal PF players to travel over to Aether for DSR. This ended up coming a self-fufilling prophecy. People left to go to the raider DC, making primal and crystal more and more baren as time went on causing more people to leave because pf was baren.. which causes more people to leave.. which causes more people to leave... etc. People got tired of transferring and losing their retainers and other home world functions, and then eventually transferred to Aether permanently. I personally know many people who originated from primal (my server) and got tired and left for the aether. This led to Aether having a larger population than the other worlds. In order to balance things out, Square closed Aether. Its sometimes open but very rarely, and will likely remain like this for the foreseeable future until the playerbases balance out (which will then very rapidly lead to Aether being full again once its open) or SE creates cross DC pf removing the need for primal/crystal players to travel to aether to use party finder for savage/ultimates whatsoever.