Going by the trailer, if we only delayed the daedra invasion.. will we have to return to the fiery hells of oblivion once again?
I would not mind at all... it would make a great counter to the snowy peaks of skyrim.
but rather than a series of cut/paste 'gates'.. have oblivion as a definate seperate landmass which will always be the same, and have its own world map thusly.
The trailer didn't say we only delayed the daedra. They were talking about dragons, either literally or metaphorically. My guess is it will be the ka'po'tun as they are the only dragons that have been relevant in lore as having a grudge against the empire, or it will be totally new lore involving dragons. The ka'po'tun only have one dragon that we know of (their king), but it was a long time ago that he became a dragon, and its very possible that more of his people have become them as well.
Either way, I'm certain we will return to Oblivion, but it will most likely be in side quests (i.e. the daedric shrine quests) and not within the main quest.