At this site: you can find out what Rick confirmed for the new series at the Met. Lecture.

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.