Can we have the option to pick an heir in advance? It could be a feature that players could toggle on or off through their profile or through the retirement page.

Choose an heir and pick your settings (name, looks), and when your king gets old enough or dies, the heir automatically becomes king.

Shadow King #77712 made this suggestion:
"....perhaps, when your king dies, you are given a pop up that says,
"Are you sure you want _____ to be king?"
the name would be a link so you can check it first."
For just in case a player sets an heir, but ends up getting a different lion that would make a better heir.