I don't know if GOG will be interested in carrying it at all, actually, they've been a bit mysterious at times about what games they will and won't accept. They might be okay with Black Closet since it's less anime and more game. They've generally banned visual novels there, and there was a lot of outcry when LLTQ first launched from people thinking it was something pervy!
The biggest difficulty with GOG is that it is more awkward to release updates there, since I can't do it myself and have to package new versions, upload them to GOG, email GOG, wait for one of their staff to go over all the changes, do their own testing, get back to me, have both of us sign off on it...
And so especially with a game like this where a LOT of tweaks are being made (along with the bigger content updates), a GOG release could be a mess. I may ask them about it later when things look likely to be stable for a longer period of time.
In either case, nobody else is getting it until the Custom Character Mode is done, which it isn't yet.