Since we don't really know where it will be placed we should limit our wishes to technical ones, leaving the lore ones for later.
I'll try to update the list as you post your suggestions. So here mine:
- Fancier Physic Engine ( e.g. Euphoria or better )
- Localized damage
- Combat Body Reactions ( i.e. enemies bumps, falls, react when you hit them )
- Emotion engine ( i.e. when an NPC is scared, from voice acting for example, it should also look scared )
- Survival Instinct ( i.e. when a NPC feels danger it should react by running for cover or duck or asking mercy )
- Stairs animation ( walking up and down the stairs )
- Climbing system ( stairs / cliffs )
From MythicalCreatures777: ( aren't these a bit World of Warcrafty ? )
- Flying Mounts
- Dual Spec
- Cheat codes
- Ability to get haircuts
- Armor Dyes
- The Sims house customization engine
- Mudkipz
From Silverhammer:
- Technology has come far by then, the region is Tamriel as a whole
- Set 200 years after the events of Skyrim
- Crossbows, spears, levitation, mark and recall are back
- Dremora and Falmer are added as playable races
- Available mounts: Horses, dragons and Silt Striders
- You can see areas from previous games now that you're in Tamriel, like remains of an Oblivion gate, or the Shrine of Akatosh
- The original guilds for Cyrodill, Morrowind and Skyrim
- Other, more fun guilds like the Swimming Guild in Black Marsh, the Hiking Guild in High Rock, the Hunter Guild in Summerset Isles, Necromancer Guild, Speech Guild, Smithing guild
- Carriages available as fast travel, you can just sit on them and enjoy the ride, or fast forward
Others:
- Collision based attacks, not crosshair based. (Maegfaer)
- Interactions with other people. Hold hands, hug and things like that. (Gwynbleidd)
- Hook and rope system as implementation suggestion for climbing ( TheDogBiter )
- Divisible currency (gold and silver coin) ( TheDogBiter ) * This one should be checked with the Lore
- Ability to set traps with trip wires, pressure plates ( TheDogBiter )
- Optional quest markers, but longest and better detailed quest directions ( TheDogBiter ) * This is one of my favorite!
go on