i think the in game generation cycle wil be 100 years, not because of children or whatever method they are going to use to move to the next, but because characters will live to roughly 100 and im sure everyone is going to play that character to their end before 'beginning the next' or whatever happens. I am excited to see how this system will work. I think having children would be the best way to do it, that inherit your land and some stats but with some kind of bonuses so that losing some power isn't something that you dread happening. Anyway whatever method is in place, might not be seen for a while and will probably be revealed when it is needed, not from day 1. but who knows.