If someone can link me to where Bethesda officially states that Skyrim takes place over 200 years after Oblivion, then I'll believe it. Until then, it all just sounds like crazy speculation with little in the way of proof.
I have no proof, but my reasoning comes straight from the trailer. "The Elder Scrolls told of their return. Their defeat was merely a delay." And then something that I can't for the life of me decipher what the narrator is saying about the time after Oblivion opened. To me, it suggests some new threat relating to the Oblivion Crisis. And dragons.
The narrator says
"You should have acted. They're already here. The Elder Scrolls told of their return. Their defeat was merely a delay
til the time after Oblivion opened when the sons of Skyrim would spill their own blood."
"The time after Oblivion opened" is very vague, and could mean anything from the day after the first Oblivion gate opened during the Oblivion Crisis, to two hundred years or more after the Crisis.