I think the fourth book will go back in time to show Brom and the man who mentored him discovering Galbatorix as a young man with immense talent for dragon riding and they will take him back to the capitol city where the dragon riding council will deny his admittance into the dragon riding academy. The kicker they find him in the same village that Roran will later grow up in.
Well, from what I have read Book 1,2 and 3 I assume that eragon will try to take revenge on behalf of orimos and he and saphera will be crushed and just manage to get away and the elf's the varden and the urgals will all have to leave alegeasia or how ever you spell that for ever because that was his fortune and that little girl will be the one to beat galbatrix.
everyone is intitled to their thoughts that was just odd though
i had a strange thought
the meona tree she said she would want someting from eragon what if she didnt actually take it yet what if she wants his love and devotion
this is far fetched i know but wht if she regains her humaniod form and her and eragon end up togrther? she was royalty and she is a jealous lover wouldnt that seem like something she would do and take from him if she could. plus he is supposed to fall for royalty she is and it doesnt have to be arya..
thats far fetched i know and not very probable but it was a curios thought none the less
god i want the next book to come out already