Fallout London’s Coming, You’ll Need To Downgrade Though

Good Bye Next Gen Update, Hello Croyden
Team Folon have found a way to release their gigantic total conversion mod of Fallout 4, and while we don’t have an exact date yet, Fallout London is coming soon.  The next gen update, which launched just days before their original release date managed to ruin the mod, with all sorts of new bugs and game breaking behaviour.   They tried to overcome the challenge, but there are just too many things on the back end which make their mod unusable.
Instead, they have developed a “downgrader” to restore the old Fallout 4 and integrated it with their mod to ensure those that want to play the game don’t have to jump through complex hoops to be able to do so.  GoG have stepped in to assist, first because the sheer size of the mod would overwhelm Nexus Mods and the other usual sources for your mods, secondly to package in the downgrader into those files. 
The lack of a release date is due to troubleshooting being done at GoG; they want to ensure to minimize the difficulty of the Fallout London install as well as limit the number of Bethesda bugs that make it through.  There is no indication you need a GoG version of Fallout 4, GoG will just be the distribution platform for the mod. 
Cheers to both Team Falon and GoG for persevering.