In size and in scope, not in story. I don't need to see the next game's Dragonborn killing Templars and unraveling alien conspiracies.
Seriously, I love Skyrim, Oblivion, and Morrowind. They're great. But I'm bored of how small they are. I'm bored of how they scale down the world, trading off epicness for the sake of detail.
Bethesda's proven how great they are at creating nine or ten walled towns with ten or fifteen buildings each in them. But if they do that again for TES6, I'll be disappointed. I'm ready for more. I'm ready for the Battle of Bruma and the Battle of Windhelm to be enormous clashes with hundreds of troops fighting at once, as they were meant to be -- not minor skirmishes between ten or twenty NPCs. In the lore, Solitude is a kingdom, not a town! It should be enormous, the size of King's Landing from Game of Thrones, with thousands of people in it. Not fifty.
In short, I'm ready for a change. I don't want Bethesda to recycle the Oblivion and Skyrim model again. I'm ready for Daggefall 2.
Here are some things I don't care about, and I'd be happy if Bethesda abandoned them:
1. I don't care about being able to interact with every NPC. Fill the streets with random schmoes going about their business, like in Assassin's Creed. You can have fully voice acted and scripted ones there too, just mark them with a star above their head or something to make them stand out from the rest.
2. On that note, I don't care about every NPC being fully voice acted. I REALLY hope Beth gets away from having every NPC say something to you as you walk by them. That's not realistic, nobody talks to me in real life when I walk by them on the sidewalk and Jesus little girl if I hear you say you can't get good sweet rolls anymore in this skeever nest of a city one more time my head's going to explode.
3. I don't care about every interior space having a unique room model. I thought the way Morrowind handled interiors worked just fine, i.e. the way its rooms and corridors fit together like tiles or pieces of a jigsaw puzzle. Sure, special locations can have a unique interior, like the College of Winterhold or the major castles, but having a unique interior for every shop is just overkill.
Here's my dream for TES6. It'll never happen, but whatever.
I firmly believe procedural generation is the future of world building. I want to see Bethesda really nail down procedural generation -- not just in the wilderness, but in towns, cities, and dungeons. I want cities the size of Damascus or Venice from Assassin's Creed, with thousands of people in them. I want my thief to have hundreds of houses he can hit in a single town. And I don't want there to be just nine or ten major cities -- I want there to be hundreds of them. Give me Daggerfall with 2014 procedural generation instead of crappy 1996 procedural generation. Give me back random quests, so I have something to do when I'm bored and I've done everything else there is to do in the game, so the Fighter's Guild can send me off to kill a randomly generated werewolf in a randomly generated dungeon for a randomly generated reward. And on top of that, give me the voice acted, well-designed, made-by-a-human quests that Oblivion and Skyrim are so known for. Random quests and procedurally generated towns can co-exist alongside quests and areas built by hand; these aren't mutually exclusive.
tl;dr: Take the best elements of Daggerfall, Morrowind, Oblivion, and Skyrim and fuse them together to make something that's truly epic in scope and in substance.
And bring back spellmaking too. I miss it.