There's a new anniversary edition for the game (The 7th Guest: 25th Anniversary Edition) being released on April 2nd.
It's likely that the de-listing for GOG is connected to that and we'll see the new edition here as well.
https://bloody-disgusting.com/video-games/3551575/classic-fmv-horror-game-7th-guest-receive-25th-anniversary-edition-april/

Why? That isn't Steams, or Valves, fault. That all is on Nightdive and Trilobyte. Mostly Trilobyte.
From a quick read that remasters sounds actually less frustrating to play than the original.

I hope previous owners get this or at least we get a hefty discount.

Published by the same people that did Simon the Sorcerer Anniversary. Probably a 50% discount.

Then meh, I can use my old version :D

I never bothered with the Simon Anniversary Edition, but at least this one has lots of extras, and includes the multiple audio languages and subtitles which is a big plus in my book.
Also, they will allow to switch to the classic version like some other remasters did, so that's also welcome.

I'll seriously consider it re-purchasing it, if GOG distributes it too.

Oh, no! I really wanted this game, I missed this thread and now it's too late. I wish notifications for games to be removed were more visible or, even better, we could get an email if we have the game on the wishlist. :(

I hope it will be back on GOG some day.

I think the delisting of 7th guest is for the 7th guest remaster version.
the 7th guest remastered has been announced. Game has a steam page.
https://store.steampowered.com/app/1044340/The_7th_Guest_25th_Anniversary_Edition/
I think the gog page could be arrived soon

The 7th guest remaster version seems to be a port of android version released in 2015.

And another Beamdog like company borned .

https://store.steampowered.com/app/1048430/The_7th_Guest__Legacy_Edition_English_VoiceOnly/

Those are two different statements conflated into one.

1) The de-listing is likely related to this new release.

2) We are likely to see it on GOG.

The first statement is certainly true.

The second...well, that would require some evidence/reason to believe it. Is there any?

It could be the case, for example, that they removed the game from GOG solely so that no one would buy the original version on GOG instead of buying the Remastered version on Steam.

Couldn't they at least bundle the original with the remaster?

They are bundled on Steam, should be same on GOG.

Thanks for the info, I wasn't aware there was a new edition, so this is good news. I hope you're right and we'll get it here on GOG, fingers crossed. The new edition sounds ok, I look forward to see the extras and what they did to the game, but I'm glad we also get the option to play with the original graphics, audio and mouse control.

The MojoTouch Anniversary version of T7G has been on Android and iOS for a LONG time. Maybe this is an update to that version?

I don't know how they can do much in terms of upscaling. As mentioned before, the original video footage is MIA so, it is currently impossible to do a true remaster.

The Fat Man owns the soundtrack and I know he has the original MIDIs hence being able to generate higher-quality versions for the anniversary edition.

As for the dialogue audio, I'm not sure how they managed to improve it.

Still, it is good to see they have plans to bring it back to GOG.