Fallout 5 is so far in the future (coming after The Elder Scrolls VI) that it's doubtful it will even be released this generation. However, there already seems to be a pretty clear idea of where the series will go in the future, as Bethesda veteran Todd Howard revealed details about the upcoming game to the film crew making the Amazon TV series.
He reveals this in an interview with Den of Geek, where Jonathan Nolan - director, writer and executive producer - said:
"It means you have all of the benefit of beautiful storytelling that Todd and [Bethesda] has contributed to, but we also get to tell an original story within that world. As writers and filmmakers, it's just a dream come true.
I think we made Fallout 6. We know all about Fallout 5, we're not telling anyone."
This prompted Howard to confirm and clarify, and he said:
"Well, there were some things where I said, 'Don't do this because we are going to do that in Fallout 5'."
The Fallout series will premiere on Amazon Prime on April 12.