It's been awhile since I've read up on the lore of ES. As we know the lore surrounding Skyrim revolves around Alduin eating the world to start a new Kalpa. We know that this has happened before, but what must happen in order for it be time for Alduin to eat the world? My guess is that it would be directly related to the events of Morrowind and Oblivion (the integrity of Mundus has been compromised) and perhaps something to do with the escalating chaos that is engulfing tamriel. Or maybe it's just an end of the line thing and time ran out. Once a Kalpa ends and Alduin has wiped the slate, when does the new one begin? The Dawn Era?
On a side not I think it is interesting that the events of SI draws parallel to this (the Greymarch) and that in SI there were sites that were left over from previous "eras" much like how the Leaper Demon king and the Greedy Man would save pieces from being devoured. It would be cool to see places left over from previous Kalpas in Skyrim or in future games.