The GOG Preservation Program appears to be updating games to run well on Windows 10 and 11. The original OSes are no longer listed as compatible, though, e.g. Windows XP, 7, etc. Is this just missing info from the specifications of these particular games, or will they really no longer work on their original, older OSes?

It will vary on a case-by-case basis. Such changes to the listed OSes will, however, mean that GOG won't guarantee they'll still work on the now-deprecated OS versions. (I.E., Support probably won't do much to help you if you're running a game on one of these old systems.)

Basically, hang on to any old installers you have, just in case an updated version breaks something -- especially if you're sticking with an old OS for whatever reason. And, obviously, download anything you care about that you didn't already have backed up.

Yes, no, maybe, I don't know.

Can you repeat the question?

In short, it depends on the game. An old DOS game is frankly not going to care, but a newer version of Dosbox Staging isn't built for a 10-20 year old OS. With GOG finally on the train in that matter, even that's a slowly closing door.

In the case of MacOS, you're hosed. One day, the CEO might wake up with an extra brainworm and decide now's a good day to hard cutoff Rosetta 2.

It varies. In some cases GOG themselves have broken compatibility with older OS's from Galaxy integration (example Fallout New Vegas). In other cases (eg, The Planet Crafter), the game came out in the middle of W7 EOL, was originally designed to run on W7 but then a later patch used a newer version of Unity Engine which in turn was compiled to run on W10 minimum. Some games, eg, Myst (2021) default to DX12 (W10+ minimum) but can be overridden with a -dx11 command line switch and will then run on W7. Some ScummVM games (eg, Riven (1997)) say "W10" minimum yet ScummVM itself has dedicated versions for supporting even back to 32-bit Win 95/98. Some DirectDraw games (eg, Commandos Ammo Pack) used to list W7 only even though I had no problem with it under W10, and now after an update lists W10 only (even though it still works under W7)...

It's understandable why GOG don't want to support 15 year old Windows, but it's also resulted in "System Requirements means what we're willing to issue refunds for in 2025, not what the game actually requires to work" that are the least accurate / consistent vs other sites, especially for older games most of which do still run fine on W7 (and as someone said above, if the GOG version doesn't, "other" versions still do). Declared Linux support is often equally inaccurate with many games here still saying "Ubuntu 14.04, 16.04, 18.04" that they did from a decade ago (current version is 24.04). (This thread may be of use) from people actually testing in person if you're still on W7.

Are they? Is there an example somewhere of GOG switching to Dosbox Staging?
I must admit I didn't pay much attention to GOG's latest wave of updates as part of the "Preservation Program".

The latest (original) Doom Bundle uses it, to my understanding, and other games have begun to have it deployed.

Like I said: A slow door.

Also Ultima Underworld 1+2 that I know of.

GOG could of course simply crowdsource any older OS / hardware testing to us, as long as they would then use our findings to determine which older versions for each game should become unsupported installers in a new download section for those games.

Saying that we all should download and backup our games as soon as we have bought them doesn't in any way solve the fact that any customer who buys enough games from GOG is eventually going to find out that they will not have the time to test every new update in advance to know whether it can replace the previous version in their backups or not, while on the other hand if a new customer would buy NMS from GOG now, they can't try out what it was to play that game before each previous content update because at best they can rollback their games with the Galaxy client to whatever version was the fourth version before the latest version of those games and depending on when they bought NMS, that could already be the one of the bug fix patches for latest content update.

Usually in these topics someone tries to claim that GOG can't allow us to download older versions because they would have to provide tech support for them, but do anyone here honestly believe that if for example they can't get the Win3.1 prototype for Retro City Rampage to work on their computers, GOG would in any way be required to spend any actual work hours on helping to solve something like that?

At the bare minimum GOG should leave available for each game the last known compatible version for any OS versions that those games have ever been claimed to work by GOG, including the last version before a game gets this new Good Old Game treatment that sometimes manages to make things worse for some of the customers.

I would understand if someone thinks it’s odd for me to want to play something on Win 7, but I have an old Sony laptop with NVidia Stereo 3D built into it… and if I update to a newer os like Win 10, it breaks the 3D abilities baked into the laptop. Thanks for all of your answers, everyone.

Not around here, no.
There's nothing wrong in wanting to preserve "old" hardware and software and force them to work till their literal end.
That's the reason we thrive for real means of preservation, for both software (FOSS/FLOSS/DRMFree) and hardware (Right to repair and so on).

It's only odd for those that don't really understand the importance of preservation and liberty of choice.

Nothing odd in that. People sometimes just forgetting what PC means.

Just wanted to say it's not odd and there's no need to explain yourself.