Christopher Paolini has stated before that he intends to write more stories taking place in Alagaësia, and the next one is “Book V.”
From what I’ve heard, Book V won’t actually be part of the Inheritance Cycle, but rather a standalone novel and will take place after the events in Inheritance.
Here are my predictions for what will happen in “Book V.”
The Story Won’t Be Focused on Eragon & Saphira.
Eragon and Saphira left Alagaësia, so if we do hear from them, it will be short moments, likely through scrying.
The Antagonist Will Be Something Ancient
Now, Chris’ statement is pretty vague here, so I’m assuming it’s someone we haven’t heard of yet. If it is someone we know about then my best guess is the Grey Folk.
We’ll Be Seeing Angela Again
I think Angela will be living in the area most affected, as it’s how she is. I don’t think we’ll get a backstory from her in Book V though. My best guess is we’ll learn a lot more about her in the potential prequel.
(Bonus) Eragon & Saphira Will Need to Return
I’m putting this in here as a bonus because we know Book V will be a standalone novel and this contradicts my first prediction. Assuming a sequel could be written (Book VI) the people of Alagaësia need Eragon and Saphira to return. I know this is theorizing at this point, but when Angela looked at Eragon’s future in Book I, she was seeing the future of a different Eragon. Eragon’s true name has changed since then, and I believe that has also altered his future greatly.