Screw Bethesda.

Nightdive are cool.

On Steam, the remaster didn't replace the original version, it was just added in a subdirectory.

If, i the extremely unlikely case that the remaster actually arrives on GOG.com (something I have very strong doubts about given how the Doom remaster never arrived), then there is no reason to believe something different will happen and the original release will disappear.

Rule of the thumb: always download and backup offline installer.

Even not so significant updates may bring you to downgrade the game's version back.

Galaxy-kiddies will suffer anyway, though...

Why? Auto download of updates is optional, unlike Steam.

So, am I correct in assuming that only Steam users got the Enhanced version of Quake, and while both stores sell the game for the same price (and more or less under the same name), GOG users only get the original version (without original music) and Steam users get two versions for the price of one?

EDIT: I see this is already acknowledged in the "Games That Treat GOG customers as second class citizens" thread.

GOG version have complete and working music.
GOG version is not just original - it is clear original version. Not just readded files. It is not true that enchanced in sub-directory - original does. And moving it some fiels are missing. Not ritical... and critical at same time. It not like we have pdf files (scan are rare\lost), now we dont have proper text-based manual and read me - the only place where plot explained.

GOG version stay not just original - but most close to originally installed game+addons. +music presented as disc-image.