Paiolini has talked about writing the prequels at a later date, but book 5 is already plotted out and has a sudo-title. Book 5 will take place some years after the events of inheritance. Details about the antagonist and protagonist have not been revealed. Hints to what to expect have been forthcoming however. These are all of the details that I am currently aware of:

1) The community has largely missed a problem that has been hinted at towards the end of inheritance. This problem will play a big role in the events of book 5.

2) He intents to feature several characters that we are familiar with including Eragon, Arya(their relationship will be further investigated) and Angela. Angela will have far more of her character revealed.

As we have not been told how many years have taken place between book 5 and inheritance, so we can only be confident that the longer lived characters are likely to make an appearance. However if the time difference is short enough I would expect to see Nasuada and Roran. If they die in the interim it might also be interesting to see a chapter from Ismira(daughter of Roran and Katrina).

Any ideas on what we missed at the end of bk. 4? Even just theories.

The insane dragons mayhap? There were also all those areas Glaedr mentioned as being dangerous beyond Alagaësia, so perhaps they’ll run afoul of them.

Can't wait for the next book. I also have a bunch of different ideas to talk about.

The Discussions are open to you :)

1) A book about the turmoil of the Empire

2) The Varden as told by Ajihad

3) Brom

4) Angela (although the mystery is good enough)

I think there could be ministories or so for:

5) Orimis

6) Eragon's Mother

7) Joed

Just an idea for book 5 could be the Murtagh and Thorn finally return to Eragon but badly injured from one of the areas Glaedr had warned about. There could be a new group of riders from those areas that are mainly users of dark magic

Anything is possible!