Well I wouldn't base Oblivion coming out 4 years after Morrowind as saying that the series comes out every four years,
Lore:Skyrim - UESPWiki
I certainly hope that if it does take place on one continent, they can keep the game environments varied enough. Skyrim will be mostly all snow just like Cyrodil is composed of large forested regions. I don't know all about Tamriel, but there might be a better land.
You can likely cross off Hammerfell, High Rock, Cyrodiil, Morrowind-Vvardenfall (and bloodmoon area isle northwest of Vvardenfall) off the list of lands the next game will encompass.
I would like to play in both Valenwood and Elsweyr for the next game. They are both right next to each other and about the size of Cyrodiil.
- Elsweyr, the deserts and jungles to the south of Cyrodiil, home to the Khajiit.
- Valenwood, a densely forested area to the south of Cyrodiil, home to the Bosmer.
Black Marsh would be cool too (Argonian homeland), but if you read the ElderScrolls wiki, the primary mode of transportation is boat, so that probably wouldn't be that much fun, but I am sure the developers could work something out. Frankly, I just want to cross zonal boundaries.
And I do not think Bethesda is going to end up leaving the crap things about Oblivion in there. They upgraded significantly from Morrowind to Oblivion and somewhat to Fallout. And who is telling what type of technology will be available for the next consoles and how their engine will be in 2011 or later.
I want to go back to Morrowind eventually, which has the most mods ever for a game (probably), as I barely even got far into it. Always was just near the first town even though I put many hours into it. The reason I don't want to play Oblivion with mods is I did literally everything possible in that game on Xbox, so I don't want to replay such a game that i totally completed even if there are decent mods.
There does not need to be an MMO ElderScrolls. All there needs to be is 4-8 player coop and maybe a battle arena.
How ya doing, buddy?