My bigger question is... erm... what more is there to tell of the Dragonborn? The whole point was wrapping up Alduin, right?
I mean, what happens? Everybody's sitting around Whiterun's Dragonreach - eating dinner while overlooking the land, and suddenly a book entitled "Legend of the Dragonborn: Part 2...adenim and foot notes" comes flying from over the horizon and slams right into the Dovakin's soup?
Perhaps not so much that, but a "what becomes of the Chosen One when his role in history is fulfilled?"
You're a big powerful entity that absorbs the souls of dragons...Surely there is something more that can happen to you regarding that. And banishing Alduin didn't cure the Dragon Problem, there's still dragons. The issue is dealing with them.