Primarily for two reasons:

• I believe the Aldmeri Dominion/Thalmor war will take centre stage. It was an unresolved plot in Skyrim (or more accurately, merely Chapter 1).
  
• The subtle hint at the end of the CoW questline which could suggest the home of the Altmer being the next location.... For spoiler reasons, I won't specify it, but it is what is said to you after the final battle.

As for the two other popular options -

Black Marsh.... perhaps its just me but a stinky toxic swamp full of lizards has way less marketing appeal? I am just thinking in the perspective of Bethesda/Zenimax, I personally would enjoy this location... but Bethesda obviously want to make as much $$$ as possible (especially due to how successful Skyrim was) so perhaps they are unwilling to take the risk of alienating the "casual" base by such a radical departure from generic traditional fantasy? Also, there'd have to be some pretty big canon Lore changes.... considering only Argonians can survive in the swamps.

Elsweyr.... Personally I think this is the second most likely choice. It's environmentally different enough from previous games without being risky, and it's bordered to the Aldmeri Dominion and thus could still focus centrally on that story..... Having deserts and tropical forests would be an abrupt change from the snowy mountains of Skyrim...





But for me... I would love to go to the home of the Altmer...... I'd love to see a bit of Wind Waker-ish play elements (given that Summerset Isles is a series of islands) .... Being able to craft a boat, and sail across oceans.... And Tes6's version of a "Dragon" - the big bad monster in the wild - could be a kraken, the monster squid from old lore..... Hmmmmm..... Imagine being on a boat sailing in the open seas and gigantic tentacles come out of the water... !

Anyway, thanks for listening to me ramble.... What about you?

There is an http://www.gamesas.com/topic/1330470-official-beyond-skyrim-tes-vi-5/ and a thread debating the next location on the first page.

And I actually want to see High Rock with a Falkreath/Lancre/Hamlet theme.

Ah, thanks for pointing that out.

Elsweyr!
*tail swish*
Ra'vhash can dream-.. Ra'vhash misses his home.

Why not Valenwood?

I hope it's not Elsweyr.

I really, really don't want to live in a land brimming with cat people.

I'd live to see Valenwood.

Why you no choose Valenwood !! lol

.. anyways. I think Summerset Isles would be awesome, but i would rather they focus on what's on Skyrim such as bugs, glitches, memory problems, hard-drive problems etc. Also .. why not make it DLC for Skyrim instead of Chapter 6?

Summerset Isle is called Alinor now. The Thalmor changed the name. (Probably because it'll sound cooler than Summerset Isle as the next game title)

I think Alinor sounds a lot less cool than Summerset isle lol

Alinor is city in Summerset Isles.

I'd like Black Marsh and I think it has more market appeal, no less than Skyrim. Who says games in strange places with alien races aren't market friendly should ask how many people play tauren, worgen and gobblin in WOW and why.

The Island is indeed called Alinor now.

http://www.gamesas.com/topic/1330470-official-beyond-skyrim-tes-vi-5/