As long as you keep a pc with the specs and OS of the time the game was released. GOG is also making an effort to patch these games to make them run on current hard- and software without the hassle of finding and downloading fan patches, running emulators/virtual machines and all the other hoops one might have to jump through to get an old game running.
Of course you could theoretically pirate the gog version after they made it run, but given that these games usually cost about 5-10 bucks and some go as low as 1-2 when on sale, i think that's worth it to support these efforts.
You are right, they are doing good work to help make sure these games run.
One point of clarification though, they are pulling in the fan-patches themselves and building installers to install the emulators/vms as part of the installation. So they aren't updating these games, they are creating an environment where, regardless of how things change, these games will be playable.
What this means for the end-user is that any mods or other fan patches can still be used, because they haven't changed any of the game's code, so they are actually doing a better job at preservation than many of these companies releasing "Remastered" versions of their games are doing.
https://www.gog.com/en/gog-preservation-program direct link to GOG, because the link provided in the The Verge article is goskimresource that is blocked by my browser extension uMatrix. From the original articles FAQ at GOG:
What about macOS and Linux?
The GOG Preservation Program is currently Windows-only. Our priority is to preserve as many games as possible under the Program, before expanding to other operating systems.
Sad. How about supporting Linux? This would be the right direction to preserve games, as they are no longer tied to the Windows operating system. That's why I use Steam and do not buy on GOG.
Wait, why Steam? GOG only sells DRM-free games. Any Windows game that works through Steam on Linux, works downloading it from GOG with standalone WINE. Or via things like Heroic Launcher, Lutris or Bottles.
I can understand that their priorities lie with Windows initially. I also prefer Steam for their amazing linux support, but for preservation Steam is also a mess: delisting of games / the fact that the games are not DRM free. A copy you buy on GOG is yours forever, a copy on Steam is less certain. Also know that GOG operates at a fraction of the budget that Steam has, so they don't necessarily have the money to put someone on linux support too. But hopefully in the future this will change!
Yes, the DRM free games is a huge win for preservation. I'm not discounting the value of GOG. But that's something we had already. My critique was about the focus on Windows only, which is not the best idea if games should be preserved "forever". Because Windows 11 will be the only supported one soon.
But any efforts trying to make games work forever is always good. At least they didn't rule out other OS in the future. While my initial reaction was a bit negative in the nature, because I was very disappointment, I'm still happy they do something about it. It's even more bitter because they supported Linux in the past... But let's see how this is going. I don't want to end this in a negative note. I mean it can only get better with such a goal.