PixelBoy: Those games are not going to leave Steam.
What would have been a good idea though is redeeming games that have been bought from Telltale store, either on GOG or Steam.
The store to offer that would have gained some goodwill from people, and also Telltale would have ensured that people who have bought those games earlier could still have a place to download them.
But no, the last I heard they simply shut down Telltale servers without any word or warning to customers. Fortunately I was able to download anything that I had there, some others were probably not aware of the situation and lost their games.
The Telltale site and download servers are still up, but could go down at any time without warning.
I really hope there'll be some way for those of us at risk of losing games there to redeem them on GOG (or Steam, but GOG would obviously be preferable). If GOG can give away free copies to people who wishlisted them, presumably they must have had some sort of deal with TTG, and can try and work out another one to figure out a Connect-esque redemption system.