tweets published yesterday, the company is working to bring Fallout, Fallout 2, and Fallout Tactics there "at the earliest date possible."
The games' removal from portals, including GOG, was precipitated by Bethesda taking over full franchise rights on January 1, 2014. Bethesda reached a settlement with former holder Interplay back in 2012, after years of legal dispute that trace back to Interplay's plans to develop a Fallout MMO.
As for returning the games to GOG, which gave them away for free in its recent winter sale, Bethesda tweeted it'll "have a look at other options once we handle Steam." We've reached out to the company for more details.