So what now? (possible spoilers)
Does he marry Taka (just Japanese tradition get in the way of things like that), raise the two young boys as his own and live out his life in that village teaching and training up another young generation of Samurai?
I found it strange that Algren could do battle against Japan's army and then walk around freely, also, they went to such great lengths to get rid of Katsimoto (taking 2 armies against him and sending masked Ninjas to kill him) but then just let him walk around freely and visit the Emperor and come to counsel meetings and not kill him or arrest him (he actually was free until he wouldn't take off his swords).