Red_Avatar: It's very easy to create a package that will play a certain game, but the sore point is the rom files. As long as Cloanto refuses to make these free or doesn't find a way to integrate them into the game file (essentially stopping people from ripping them out), it won't work, however.
Correct, and that was what I was suggesting, a kind of digital wrapper that isn't a standalone emulator
per se but a self-contained emulator for just the game(s) in question. There should be a way to create such an environment, but again, the question is whether it would yield profitable returns (and whether Cloanto would allow it). As has been mentioned before, it may require a per unit cut to Cloanto to pay back the licensing cost. And in that scenario, they might in turn insist on DRM to "prevent" sharing that would deny them their cut. Which would take GOG out of the running again.
(I scare-quote "prevent" because we all know DRM prevents sod-all, except perhaps when it prevents legitimate purchasers from playing or backing up the game they bought.)