randomuser.833: Who says that GoG would do such work for games on the list? GoG doesn't own the games.
It is more to show the IP owners, that there would be some marked, that could make them some money. And if the demand would be big enough, there would be money a small devteam throwing a emu on the game and calling it a day.

And in the past there where a few old console games ported to the PC and then sold, if I remember correctly.

Yes, games in the program can be "patched" by GoG to make them run on a new windows or whatever.
And sometimes GoG made a game run again and got it exclusively for some time or maybe they get a small margin till today, who knows.

But the List is not "GoG, do it" but a showoff of the possible marked in the first place.