I'd like High Rock. Ah, and after that, Summerset Alinor.

I find High Rock most likely, but I'd be most interested in Hammerfell.

Few things wrong with your idea

High rock already had its own game.
Concerning the map a lot of what you checked off as "ash" is most likely restoring to normal for Morrowind due to red mountain erupting ages ago and even on the coastline you have it wrong since a lot of those places are known to becoming revived.
A lot of cyrodiil is actually rebuilt during Skyrim since the great war happened 30 years before the events of skyrim.
Black marsh I'll give you that.
Hammerfell could probably get its own game even if it has seceded.
Also Elsewyr is dominion territory.

I want hammerfell tbh. pirates, deserts, etc.

Anything will be great, but I'd prefer Black Marsh or Elsweyr. Whole different level of culture, survival and exploration.

I hope for Valenwood dammit i want to see big green lush forests again, i miss them from Oblivion plus i miss hunting too.

We've been there in Arena. I wouldn't mind seeing their interpratation with today's engines.

After Cyrodiil and Skyrim (both of which have been fairly traditional fantasy) I think it's time for another unusual Mer province, or a beast race province.

And who's to say the next game won't be set much earlier than Skyrim's setting, or much later? Trying to guess the next province by looking at the most recent status of Tamriel based on lore seems kind of futile to me.

there are more reasons to play in Summerset isle than in High Rock but yeah i would like to see it still i would like black marsh or elsweyr for TES VI! or maybe both that would be nice!

Elsweyr is just a desert and Black Marsh is just...well...a ,marsh...

There has been very few news from highrock and lore. I really doubt bethesda forgot about it when making skyrim. So imo it does seem like the next game will take place there in this timeline or a dlc to visit one of the citys there like tribunal expansion for morrowind.

Let's use the http://www.gamesas.com/topic/1353456-tes-vi-location-official-speculation-thread/