During the closing ceremonies of the 16th year of the 4th Age Winterfest (2015), Xahu would have made the announcement that his son Alynn Fu Sheng was to be named crown prince and his successor in place of the then heir-apparent prince Valric.
The reason for the change would have been technical: Alynn had more experience with the day-to-day ruling of an empire and the social administration of Lismore, while Valric was heavily military educated, and Xahu felt it more fitting to have a successor brought up as a ruler than a general.
Should the Heavens choose Alynn to be unsuited for the role and not grant him the Mandate, Valric then would be the next in line for the throne, and so on and forth as the family tree goes.