topolla: Why do you think so? Where it come from that the steam is any solution in this case? Steam changes installation process even more often and there is no alternative.
Maybe am I wrong but I think it's not too hard to change solution for older games. I mean separate rom(source) and make patch which changing it for OS.
Nobody has problem with patching. Preparation for new OS is some kind of patching process but before user get the installer.
To be clear. I don't expect gog to patch old system installers. Just make last working installer available for user.