This has now been confirmed by Dean Carter, who has been the project lead. The primary reason behind it is the fact that the file is too big. Currently, the size of the game stands at 30-40 gigabytes.
Recently, Dean Carter informed fans that Fallout London has been indefinitely delayed. While sharing this news, he also confirmed that the game won’t be arriving on the console. The current-gen update of Fallout 4 arrives two days after the release date was planned. This would lead to the mod breaking apart upon its launch.
This would lead to a limited number of fan creations being seen on the PlayStation mod page of Fallout 4. This also means that Fallout London will not get a release on it.
Fallout London has often been described as a fan project by many. Through this project, a new game is being created inside Fallout 4. The game is set in London and will be responsible for taking the series out of the peripheries of the United States. The game, among other things, shall feature a bunch of factions that would fight among themselves to assume control over London.