WolfEisberg: GOGs revenue hasn't increased with the increase of over all PC Gaming revenue. Fir nearly a decade GOG has only seen 34 to 45 million USD in sales each year, and with the exception of releases of Witcher 3 and Cyberpunk 2077 where gog got more.
I suspect in 2025, even 2035, gog will still be at 35 to 45 million per year except for when cd project red releases a game.
Sadly Steam has too much of a stranglehold on PC gaming.
I suspect GOG really got their initial foothold in the market via exclusive old games on new machines, combined with their DRM-free principle coming about in the era of when DRM was still a pain for PC gamers. Now that even old games come to Steam (sometimes even the GOG version of a game, and I imagine some people will just wait for the GOG version to come to Steam) and most gamers consider Steam acceptable "DRM" (whether one considers Steam DRM itself or not, I'm not interested in arguing with anyone over it), the average gamer doesn't have a reason to shop here and split their library, unless they can't get the game on Steam. (Plus Galaxy never really took off.)
GOG dropping DRM-free would be more trouble than it's worth, but imo GOG's nicheness is something to keep in mind when there are complaints about the lack of "exciting" big-name mainstream releases; granted those complaints are pretty rare. (We've gotten some since late summer-ish but the first 6 months were devoid.)