Think about it. People think they died long ago and there clans are scattered about. But if you really think. It may be false. They are hiding and are thriving with there clans powers and can lead to the attempt to seal Madara! That would be awesome if Sasuke were to get some cool sealing stuff and Naruto is tailing him and learns about his clans origins.
(Thanks Ldude you made me think of this...which was worth a thread...idk)