It seems some of you are taking it as a certainty there will be six saga boxes? What do you base the assumption on? Is there a visible proof in one of those campaign logs they mentioned?
It would be great to have that many, and it would make sense, since there are six books in the LotR novel.
Now though, creating 24 heroes can be tricky, if they are going to be based on the books only. Certainly manageable, but only with many duplicates of those we've got already.
If you think about it, in a way the game has only scratched the surface in terms of development of most of the main factions; however, we've already seen a vast majority of the most important characters. It seems obvious we will see many, probably most, if not all, at least twice throughout the game (hoping the game will indeed continue through all the six saga boxes and parallel cycles).
A side question, how many cycles will we have seen before the final saga box is released? I'm torn between two or three (after AtS, of course). Even if you "only" get two more cycles before the saga has finished, it will be 16 more heroes.