At this site: you can find out what Rick confirmed for the new series at the Met. Lecture. http://www.mortalnet.com/losthere/
For those of you who don't want to go there, or are just too lazy, I'll list them here.
- The new series will revolve around the prophecy made by Rachel in The Last Olympian.
- We will see Annabeth’s architecture of Olympus in it.
- Percy will play a very important role in the next series but he won’t be the central character.
- Characters of the Percy Jackson series will appear in the next book, and Percy and Annabeth will be very Active in this new series.
- We’ll be introduced to a new set of characters.
- We will meet new monsters and gods in the series.
- Rick will include the new myths he heard about in his next series.
- The story lines of the Olympian universe and the Egyptian universe won’t cross.
- There will be 5 books in the series.
- They will be longer books.
- We’ll have a twist in the next series.
- There won’t be too long of a break between The Last Olympian and The Lost Hero.