I was under the impression that the main setting for the game is a sort of dragon retreat/crazy laboratory. That's why there are skeletons of dragons everywhere inside. In addition, there are drakes all over Dark Souls so it still doesn't rule anything out. I'll rewatch the trailers and see if I missed something...
I think we know very little about the main setting. We've seen some areas that are being worked on, with the laboratory and that place that has a bridge that looks very similar to the one you cross going into the Painted World of Ariamis. But no real indication that those are the main setting.
A few things we do know:
- With the existences of the bonfires, Gwyn has obviously linked the flames, so it certainly can't be before that happened. However, one of the more recent trailers shows the player actually extinguishing a bonfire. What in the world could that mean?
- The setting seems to be much darker and foreboding than Dark Souls was. It's like they've taken a throwback to some of the more stressful areas of Demon's Souls and added those horrifyingly awesome elements to Dark Souls 2.
- Dragons (Wyverns / Drakes?) everywhere. This certainly puts us at an earlier time frame than Dark Souls, as they're nearly extinct at that point in time. Only the Everlasting Dragon in Ash Lake, the Hellkite Drake (and the lesser drakes), and (technically) Kalameet are left in a respectable form. Everything else is insane (Seath) dead, decaying, or really malformed.
- Having said that, I suppose it is possible that since the game exists in another part of the world (essentially polar opposite location from Dark Souls, according to Fromsoft), that it wouldn't be so far fetched as to imagine there still being a remnant of a lesser dragon population. Or perhaps someone figured out a way to create them?
I should probably go back and re-watch everything, but I think we're looking at a prequel, or at a minimum a concurrent storyline that interacts little with the events in Dark Souls. Honestly we don't know enough. They've released enough to make us all go absolutely crazy but not enough to tell us anything. I guess that's about par for Fromsoft!
re: Jelle - I would point you to youtube actually. EpicNameBro, VaatiVidya specifically. Maybe someone else has a more lore oriented forum that I'm not aware of. The wiki forum is pretty crowded and it can be hard to find good stuff there amidst some of the spurging.