I've heard conflicting reports about but yeah I personally think it's going to end up being pretty large. Found this too regarding it.
EDIT: Big scansTwo of Tecmo Koei’s popular series, the Warriors games and the Dead or Alive games, both games that have a wide range of characters to choose from. Famitsu asked about whether we’ll see a similar selection in Hyrule Warriors.
General producer Hisashi Koinuma agreed that the Warriors games’ main appeal is partly the action and partly the vast amount of playable characters.