VeldrinMaven: I am pretty sure it will come to GOG. They even released it on consoles, so why not on GOG. Just a bit more patience. GOG is not the biggest priority, but GOG is growing and it will be a bigger priority in the future, no doubt about it. DRM-free distribution can be success for all.
The problem with any game that isn't a day one release on GOG, is that the number of expected sales on GOG is slowly plummeting. I'd imagine that the sales number for Axiom Verge, has already reached a minimum, and if the publisher doesn't see enough profit, they'll just not release it here at all.
People will have ended up getting it on consoles/STEAM, or worse as you can see from this current thread, they will be pissed with the developer/publisher and swear off buying the game, even if it does make its way on GOG. You can check several posts near the beginning of in this thread, where people state that they'll not buy it anymore.