Awesome game! Here's an idea: why won't you make the game about the protagonist's family, with a system not unlike the one in Crusader Kings 2? You could build an entire life simulator with finding a mate, having kids, and so on, and when the main protagonist dies, you can choose one of his children to succeed him and to play as them next.
Thank you :) Man it's one of the best idea I've ever heard!! And it fits completly my idea since you are playing a tribe mate, I'll just focus more on his life. And when he dies, you can switch to one of his children so the game has an infinite gameplay, really interesting :D