Edit: Skyrim on Wiki http://en.wikipedia.org/wiki/The_Elder_Scrolls_V:_Skyrim
I also know Skyrim takes place 200 years after the events of the main quest in Oblivion. From the little I know(and if anyone has links to specific details Id love to see them) of the period between the two games the Empire's government essentially collapses. A DLC would NOT have to take place near the end of that 200 years, it could be as little as 50-100 years after the events of Oblivion's main quest and really just set the tone for Skyrim and witness the events that started the turmoil in the Empire.
I am sure Bethesda could garble the lore a little bit more for it to make sense why our character is still alive, but thats kind of what Id like to discuss here. Keep in mind I am NOT a lore buff and really only have ingame stuff to go off of, I really dont mind anyone poking holes through my logic and scarce facts.
Spoilers for people who may not have finished Oblivion will probably come up in this thread, youve been warned.
Speaking of spoilers, it could be dependent on Shivering Isles since you become Sheogorath, and the effects of a mortal doing that are relatively unknown. I would think a somewhat expanded lifespan wouldnt be too far out of the realm of possibility. See what I did there?
Or the PC could just be longer lived because hes chosen by the gods or some such thing.
And then theres the second part of what Id like to discuss: What exactly COULD happen?
There is that book that was written(I forget the name) about that floating sky city, although Im unsure what time that places in and how it will relate to the story of Skyrim. If any you lore people want to shed some light Id like to expand on whatever is currently know about the time between Oblivion and Skyrim.
In the event of any sort of Nordic raids(because Id figure if anyone would take the opportunity to do a bit of raiding, it would by them) from Skyrim on the outskirts of Cyrodiil, well who else are they going to turn to if not the hero of Cyrodiil?
Or even things like slavers creeping out of the marshes or Morrowind. Fringe raids, general unrest, increase in lawlessness.
My favorite idea so far was a bit of a twist at the end of whatever happens and that somehow the PC from Oblivion unwittingly CAUSES the collapsing of the Empire. Like maybe somehow knowingly helping the assassin who kills the Emperor?