War might never change, but the owners of it do. That can problematic if you've been selling that war, and suddenly find your previous contracts have been cancelled. You know what, this metaphor was flawed from the start. Law. Law never changes. That's why Steam, GOG and any other digital retailers were forced to remove Fallouts 1, 2 and Tactics from sale (although, not from the libraries of previous buyers), after ownership of the franchise transferred from Interplay to Bethesda at the start of the new year. Naturally, it would make sense for the new owners to also want to sell their wars, and - for one store at least - they say they're working hard to do that.
Hey, Bethesda! Do you have a tweet that neatly encapsulates your public statement on the matter?
We're working to return classic @Fallout games (1, 2, Tactics) to Steam and will provide an update when they're ready to go. January 2, 2014
You'll notice the absence of any distributor not called Steam in that statement. Shortly after, responding to a question, Bethesda stated "we'll have a look at other options once we handle Steam."
As for GOG in particular, they later specified why the Steam deal is taking priority.
@karimchelli @Fallout we're not currently a publisher on GOG, which is why it's a little easier returning them to Steam. January 3, 2014
So the lack of an existing deal doesn't preclude the eventual creation of one. Which sounds positive for an eventual DRM-free re-release of the GOG versions, even if we're a long way from confirmation.
We've reached out to GOG for comment on a possible deal.