Just stop developing and pushing Galaxy. Make the GOG Downloader great again. Fix the site bugs; I say even forget the forum for a bit and make sure the store functions like a store should with proper support, wishlists, ignore function and library.
If someone in GOG's userbase inexplicably wants to buy from GOG and still want a client, just team up with those platforms that must not be named and sell their keys that activate and work on their clients.
I am sure plenty of people here like the convenience of having Galaxy around (I am one of them, even though I didn't start buying here because of clients) - and frankly, Galaxy 1.2 was a simple thing that worked well for the most part... Galaxy 2.0, on the other hand, was a ridiculous idea from the beginning, especially the way it was managed - the client to rule them all... lol. Guess they missed out on the part where that eventually didn't end that well for Sauron.
I do, however, strongly agree on the GOG Downloader revival - it should have never been killed in the first place. For as long as they keep the non-galaxy users with a less convenient experience regarding game downloads and whatnot, their "galaxy is entirely optional" stance is not very credible. It's optional, alright if you want to have a harder time downloading your games
I say keep Galaxy around for those who want it...but keep it simple, no fuss, like the previous Galaxy was. Give others the option of using GOG Downloader. Fix the glaring issues with the store and user experience that have been piling up for years now.
Then everybody (or almost everybody) wins - and perhaps GOG benefits even more from it, seeing as then it's possible for users to actually talk about the platform without having to say "oh, yes, it's DRM-Free, which is great... but the rest is broken and neglected"
As said before... this market is a very tough nut to crack and while it's not realistic to expect GOG to suddenly claim major market share (if ever), the current situation does them no favours at all. Not to mention that, more importantly, it might actually even drive some people away.
I agree that it should be continued if people use it but I also think they should allocate attention to it carefully because only they know how big of a section of their userbase uses it. I think not releasing TW3 or Cyberpunk on Linux was a big mistake because that community is more educated about DRM and gives more value to DRM-free games. But currently they're spreading themselves thin by trying to be too many things at once and I'd even say there isn't a unified idea about what they're trying to be.
GOG doesn't need to be a market leader, it has a place because DRM-free games have place. All it needs to do is just rise to the challenge of serving that niche role in a better way than how they're doing now. Hopefully they do so soon because I don't want to buy games and have to deal with 2 or more DRM hoops to play them.