Ancient-Red-Dragon: In that interview, one of the GOG employees specifically said that one of the great reasons to buy games from GOG is because if a new OS comes out in the future, then GOG's devs are going to ensure that GOG games will be made compatible with that new OS.
It's a nice promise but some stuff is simply out of GOG's hands. Eg, Microsoft already deprecated DirectDraw. Despite that the files are still included on Windows 10/11 ISO's and are installable as a feature (Programs & Features -> Turn Windows Features On/Off -> Legacy Components) - but for how long? If they get removed in future builds, many games will be broken (and some games like Commandos Ammo Pack are already not certified by GOG for W10 compatibility possibly for this reason). Since W8, Microsoft made some changes in the DWM that often breaks MSAA / VSync in DirectX8 and earlier games. Sometimes dgVoodoo (DX5-8 -> 11) wrappers works as a workaround but not always as well as natively. If you're lucky a great modding community can patch a newer DX9 game renderer in (Giants v1.5, Thief NewDark, etc) or make a great source-port. But whilst GOG can integrate those, it's mostly the modding community that's actually creating them (and not for all games).
In 5-10 years time where will Microsoft be? Deprecating DirectX7-9 too? Doubling down on the "your PC is a 27' mobile phone" cr*p complete with locked down sandboxing that kills off modding / compatibility tools? W11 recently introduced
Smart App Control which
"uses AI and Microsoft's cloud knowledge base to check every app that runs, blocking anything unsigned, unfamiliar, or known to be malicious. There is no whitelist, so blocked apps will only get through if their developers sign them". Or basically, it's an OS-level DRM kill-switch that mass blocks older games / mods by default. It's optional - for now - but will it remain so on W12 (or even later builds of W11)? No-one knows. And what if Windows 12/13 ends up Windows 365? Collecting 1,000x DRM-Free game installers seems rather pointless if the newest shiny OS it runs on suddenly needs a subscription / online account whilst aggressively blocking "unsigned" compatibility tools that causes half of them to break.
GOG has for the most part simply been lucky that for all their faults, Microsoft have (so far) been pretty good at backwards compatibility even for W10/11 and not that difficult to run offline. But as the saying goes "past performance is not indicative of the future" and such a promise of "always" having old games run on the newest Windows OS should not be taken as a guarantee in the face of some of Microsoft's 'visions of the future'...