According to John Garvin, the game director of Days Gone, the team already had a rough script and first drafts ready when the sequel was canceled. He said that the game had been presented to PlayStation management as a project and work had already begun on it. Some things had already been completed, so the cancelation came as a surprise to the developers.
However, it's worth noting that Garvin had already been fired from Sony PlayStation at the time of the cancellation, but work continued even after his departure. Garvin said that the developers had the script, setting, map and concept art ready. He also noted that the developers intended to create not just a sequel, but an entire trilogy, so the cancelation of the project greatly affected Bend Studios.
At the same time, John Garvin left hope for the future of the series, saying that "never say never". He said that Sony executives might one day change their minds and bring them back on board to make a sequel, but admitted that it's unlikely.
The action game also received a content update.