Um, i really don't know if you guys ruled this out already, but we shouldn't have clan's have their own kekkai genkai... Well, not clans made by players.... like maybe take a very hard test to get in the clan then when your reborn your in the clan and you have to awaken the kekkai genkai in certain situations, depending on the kekkai genkai... oh and maybe make like the Uchiha Village where you can only learn about the sharingan if your in the uchiha clan and the hyuuga clan village, and the ruins of um...the other kekkai genkai places. When i say a hard test, i mean like something literally unbeatable in some kind of maze with puzzles, where you have to do a special thing in the fight to get accepted. I think that different kekkai genkai's have different kinds of use styles... i mean like sharingan is to watch,wait, counter, Hyuuga is to bring the enemy down from the inside (closing up chakra points so they can't do jutsu). Yeah... well that's my input >.>;