The fathers kill each other and the kids walk home crying and swearing vengeance.
Revenge against who? You made me laugh.
Senju clan VS Uchiha clan , what Konoha ( Madara+Hashirama) is gonna do?
I don't see Hashirama and Madara sat down to watch the last brothers and the fathers fighting to death.
Madara killed some adults senju , Hashirama and Madara can be stronger than their fathers now.
I think Madara and Hashirama will try "talk no jutsu" on their fathers , but I don't see them agree...
Double KO , and then what ?
Hashi:"I'm so happy , we can now found Konoha , all the clans will come with us cause our fathers ( leaders of the stronger clans of the area ) killed each other"
Uchiha and Senju would most likely be destroyed by other clans cause the leaders are dead.
In the opposite , if the sons killed the fathers ( stronger guys of the stronger clans) , the clans would probably be feared , the sons may be seen as geniuses not to fight with , and some strong clans may accept an alliance.