I was thinking and it just came to me. How do we know It's just set in Skyrim? I mean, yes that's It's name but with all the Akivir markings and references to other provinces, I'm hoping we can venture elsewhere

True, I liked how in Oblivion you were able to go visit Cyrodiil every once in a while....

I would assume its just based in Skyrim like two of its predecessors but there's always a chance of a dlc or expasion which add's more land but hell maybe some of its based in hammerfall or High Rock for all I know

Well Morrowind was just Morrowind (the greater island of Vvardenfell more specifically) and Oblivion was just Cyrodill. I suppose it's a possibility, but I wouldn't see it being too likely. It might actually be nicer to have a smaller province as there might be more time for detail and immersion as a result. The size of Cyrodill was great and all, but come on, at least half of it was a great forest...

I wouldn't expect any deviations from Skyrim expect in expansions (Tribunal, Bloodmoon, Shivering Isles, etc).