I like the idea of story feats, but when I read the actual story feats, they are lacking. I could make something for the individual characters to fit the present/past story. And then, let the player know what they need to do to unlock the full power of the custom story feat.
Actually, that might be what I need for the initial characters. Give them each a custom story feat which is unlocked when they have produced a viable heir. Alternatively, setting up a 'wizard academy' or something similar, would count, where an apprentice is trained to continue the master's life quest. This would take some time talking with the players to see what they would have in mind. I know one player who would probably be satisfied to sprinkle illegitimate children throughout the kingdom, rather than actually raising a heir properly, so these story feats would need to be flexible, and the reward based on the character class, and the difficulty of the objective.