I want the attributes back, and the birthsigns. Racial perk trees. More responsibility for the player, less handholding, heavy consequences for our choices. More branches in quests, longer questlines for guilds where you have enough time to feel the progress is natural, relevant skill requirements before you can rank up. More ways to solve quests, more interaction/rivalry/sabotage between factions.
Larger scale cities would be nice.
Jeez, dude, way to take like half the good ideas in the first reply. I guess I'll continue.
More books. Both as fluff pieces to add character to the world and as ways to exposit Tamriel and whatever area of it we find ourselves in. It's a cheap and comparatively easy way to add and flesh out lore.
I've posted my hope/idea for how a leveling system using both perks and attributes would work in the last thread, so there's that.
The ability to see your left-handed weapon at your belt when sheathed would be great.
Whatever people think of Dawnguard's actual quest lines, it is a great example of how to bring in new lore and mesh it with the old. It's handling of the Snow Elves and Ideal Masters was great. I guess do that again but for other parts of the lore, please?
I guess a lot of my other hopes are region-specific, but if it's going to be in a relatively flat country I think it'd need to be scaled up. Cyrodiil
feels smaller than Vvardenfell and Skyrim because you can walk across it in a nearly straight line with little trouble. So if it's a place, like Alinor or Hammerfell, where a straight line might be possible it'd need to be big enough to not feel tiny when you get from one side to the other.
Also, since I hope it goes into the Thalmor, bringing in Sunbirds and other spacefaring vessels from the Second Era would probably both fun and a cool way to make it obvious that TES isn't another Tolkien wannabe.