Yes this is another idea for TES VI.
1. To get it started, let's eliminate a few obvious provinces we're sure won't be in the next game.
WILL NOT TAKE PLACE IN: Skyrim. Obviously, because they wouldn't go back after they just made a game.
Morrowind. In Skyrim, they already made a nod and gave a glimpse back to TES III. Don't think they'd do it again in a whole other game.
Cyrodiil. Oblivion was great. It's the cosmopolitan, medieval world everyone liked. So it's still too familiar for us from the last game. Part of it could possibly be DLC in TES VI, but that's just me speculating.
Akavir/any other continent. I know, I know, it would be awesome to see the land we've heard a lot about, but never in detail. I mean the NEREVARINE went there(I should know). I just don't see them doing something like this in the next game because if we go by normal Bethesda time difference, TES VI will happen a few years or maybe a decade after Skyrim(It went in pairs, Arena/Daggerfall, Morrowind/Oblivion, so shouldn't it be Skyrim/TESVI?). And nothing in the events of Skyrim would point to truly important events in Akavir.
2. Second, we can probably cross off these too:
LIKELY NOT TAKING PLACE IN: Black Marsh. Many in-game references point out that Black Marsh's marshes are near impossible to penetrate. Especially it's capital city in the heart of the province. Plus, it is home to a beast race(NOT being racist at all). I don't think Bethesda will try to pull off a game with a beast race as the main race of the province. It COULD happen, and this as well as the few after it are more likely than the others above, it is still low chance to me. Finally, again, no story or signs pointing toward it in the near future.
High Rock. A game here would be filled with court intrigue, a struggle for power amongst the distinct kingdoms. I love this kind of thing and it's very Game of Thrones-y. Bretons are my second favorite race to play as and there culture is great. But, the landscape and geography is similar to Skyrim and while I think Bethesda will play it safe and not go out on a limb with a series that exploded with Skyrim, High Rock is not far out on the limb enough.
Valenwood. In my opinion, this is one of the provinces I would most like to visit. Tree cities? Nice. But I think this would take away from one aspect of the game that was always prevalent: Dungeons. Bethesda has them in all the games and they are central. I don't see very many dungeon opportunities here. If they DO choose the home of the Bosmer, it would be very edgy and not playing it safe.
Elsweyr. Very same reasons for Black Marsh, except without the impassable terrain. This province would again certainly be a good game. Sandy deserts and buried cities(dungeon capabilities) also with jungle? A great deviation from the tundra of Skyrim. But still, no story points to it and it has a beast race home population(to which I add they would have to make ALL the types and breeds of Khajiit to live there).
3. That leaves us down to my top two picks: The Summerset Isles and Hammerfell.
Summerset Isles-Some reasons I think it may very well be in Summerset Isles:
-Magic. A major theme in Skyrim was the hatred of magic and sorcery. I could definitely see Bethesda having a magical comeback by traveling to the home of the Altmer, the race with the most affinity for the clever craft. A focus on magic in TES VI could give fans what they wanted for magic in Skyrim(spell crafting, etc...) and it could add variety since Skyrim was obviously geared towards warriors a bit.
-Mechanics. We've seen an island before, with Bloodmoon and Dragonborn DLCs taking us to Solstheim. But this is a completely different kind of setting. Altmer society is very advanced in magic and is very modern(so to speak) as compared to barren like Solstheim. A more Cyrodillic feel to the environment wouldn't be so hard, and it would work pretty well I think. If the Summerset Isles are chosen for the next game, it also might feature another province due to it being smaller than some of the other provinces. Could be Valenwood, or even Hammerfell. I don't know. Also, placing the next game in Summerset Isles would bring some new life into the series. We've seen two provinces dominated by humans in the last two games, and maybe we need more mer.
-Story. The main thing I think about when I think about TES VI and where it could take place, I first think of what has happened in the past games(crossing off things with a been-there done-that vibe) and going off of clues in Tamrielic events. The main thing I looked at after Skyrim is....the Great War. A main element in TES V, innumerable allusions to the Second Great War are made. Being the home of the Thalmor, the main antagonist in the Great War, this might possibly be the next place that major events happen for the outcome of the war(or just after it like they did in Skyrim).
HAMMERFELL. This is the most likely place to put the next installment in TES. While there is a good case for Summerset Isles, as I said previously, those reasons could be great for a DLC to the Isles instead of a main game.
Hints, Clues, and Allusions-Like I said, story and major events are what I look out for most in this prediction. I just think there are SO MANY clues and allusions to the next game being in or at least primarily in Hammerfell. Some examples? Lokir from the opening scene says he could've been halfway to HAMMERFELL if he had not been captured. Later, when you encounter the Frostbite Spiders with Hadvar(must be him) he says: "What next, giant snakes?" I think that may be an allusion to a unique new enemy to fight in Hammerfell due to the Alik'r desert climate. In Oblivion, I can remember many, many, stories and sidequests from commoners mentioning Skyrim this, and Skyrim that. I see this happening in Skyrim too. From capturing or freeing the Redguard woman in Whiterun to retrieving The Last Sentinel book for Rustleif to give his kid some Redguard heritage, to Kodlak Whitemane being a bodyguard there before being recruited into the Companions, it seems heavy on Hammerfell. The final allusion? It is the Redguard clothing and scimitars. Why are they in the game? It doesn't really make sense for them to, but they are there nonetheless.
Story Continuation. Going along with what I said in the last paragraph, in many places there are in-game references that Hammerfell is currently independent and standing up against the Thalmor. The Redguards won great battles against the Thalmor and are continuing to fight. To me, it seems like Hammerfell could be a great place to continue the Great War arc.
What could make this game great. I said Bethesda would probably play it safe. That doesn't mean they won't create a game we all greatly enjoy. Hammerfell could be one of the best games in the series. 1-desert landscape is a great change to the tundra we all are familiar with now. 2-DWEMER RUINS-these have been one of our favorite dungeons since Morrowind and we could continue to have even more of them since the Dwemer had cities here too. TES VI will be made for next-gen. Which means we could have a much bigger area to play in. This opens up possibilities of maybe some sea action? With ships and stuff? I could definitely get into that. Sailing to Stros M'kai or the other provinces if they make it more than just Hammerfell, Summerset Isles for the Great War arc, you name it.
Well, I think I have typed just enough for one night. It is two in the morning where I am.
This is just MY opinion, not fact mind you. Please make comments on your own theories and maybe on mine.