Hi, ex-Aquamarine developer here.
While the original plan for Aquamarine was, in fact, use Pretendo´s 3rd party service after Nintendo Network shutdown, we had issues with development, lack of available testers due to no easy way to authenticate unless using a proxy (even then, we couldnt decode the Juxt tokens, obviously)
Issues like this, and just a general desinterest from Chayton (main developer, leader) and him wanting to pursue other things to do outside Miiverse clones, caused Aquamarine to eventually shut down and stop development.
Currently the entire source code (AquamarineMiiverseTeam · GitHub), is available on GitHub, so if anyone with server/Node knowledge and a big and good server is interested in reviving it, good for them, i still would like to see this project finished.
Aquamarine was meant to be similar to early Miiverse, with the older layout but yet a nice UI with a lot of charm, effort, and love put into it.
The entire client functionality was wrote by me, i wrote all of the JavaScript for Wii U, implemented stuff like jQuery PJAX that made changing pages really fast (Juxt does not use this library, sadly), and made an optimized and minified code that was precise to avoid any bugs (sound playing twice, slow loading, broken button support), there were just some of the bugs that were fixed on Aquamarine that Juxt originally had and still present.
Point is, yeah, Aquamarine, as it was, its dead, the Discord server is still up but its dead.
No idea if anyone will ever rehost Aquamarine with an big enough server and if it will ever be supported by Pretendo´s 3rd party service (We know they can, as seen with rverse archive, which they currently support), but we just dont know if they want to
(Same applies for my TVii revival project, which is getting an public beta really soon, but i had to get used to the limitations that i had to deal with, since Pretendo didnt officially support TVii authentication and i had to implement a different type of authentication)
Chayton couldnt get used to these limitations when NN shutdown and it was hard to debug Aquamarine on 3DS and Wii U, he kept working on offdevice tho, at one point, i was the only one working on Aquamarine Wii U since Chayton couldnt properly proxy his Wii U, it was hell.
So yeah, Aquamarine, probably not happening on Pretendo, and definitely not coming back anytime soon