I have an idea for you guys to consider. The uchiha had a binding factor their clan which was their sharigan. The Senju were just skilled overall with huge chakra reserves and stud bodies. The only thing that held the senju together prior to the formation of the village when they were a hard clan was war. After that there was nothing to hold them together. They weren't unique from other except for the fact that they were stud shinobi. The clan and name doesn't exist in its previous form but that does not mean they died out. The most rational idea is that they reproduced with other clans and people and fell apart due to the lack of "adhesive" the clan is dead but that essence that will of fire and that Hashi drive still exist in the vilage. I name Hashi because he was the clan leader. There is no confirmation that the Senju clan member's are dead as is with other clans. if you consider this idea along with the theme of will of fire. The fact that the clan name is not seen anymore doesn't mean the clan is dead. they sewed their seed because they were great mates. When you think about it one thing becomes clear. Konoha is the embodiment of the Senju clan. That is most likely a product of the clan spreading in the village and passing down the senju Ideologies to their children.