Character dark and light scale based on choices ala KOTOR, complete with Fable's physical changes that come with these choices.
I'm going to add another "no" to that.
As for what I want (granted, it's a lot of things, and only a few, if any, would be implemented):
Melee Combat: Lots of places to look for inspiration (dark messiah, mount and blade, as have been mentioned). I liked the unarmed combat and timed counter system in Arkham Aslyum (not to mention grapples and throws), and the Prince of Persia series has some good ideas for a more active style of combat (vault attacks, dodge rolls, off-handed strikes, etc.). Of course, better horses and mounted combat would be great too.
Athletics/Acrobatics/Climbing: Mirror's Edge, Assassin's Creed, Prince of Persia, etc.
Stealth: You still have a Thief dev on the roster, dammit. I want to put out torches at range, blackjack some fools going off about rats, and carry their bodies off into a dark corner. I'd like to care about the sort of ground I'm walking on and have a need to stick to the shadows and places that are out of NPC's direct line of sight. I'd especially like for my lockpicking to take place in real-time, with guards patrolling on a regular basis, while I mutter "dammit, dammit, hurry up!" at the computer. Would also be nice to incorporate social stealth and disguise concepts from Assassin's Creed and Hitman, respectively.
Magic: Plenty of places to pull ideas from there, no surprise. I'd recommend they focus on ideas about controlling the environment rather than doing direct ranged damage (since it emphasizes the "clever" nature of mages, and overlaps less with the role of Marksman). Bioshock (particularly BS2) and Dark Messiah have some good ideas, and I like the Shield and Pyrokinesis abilities in Psychonauts too. For actually creating spells (and enchanting items!), I hope they pull some ideas from Freedom Force in terms of flexibility. I'd also love to see some army control for Conjurers in the vein of Overlord, a squad shooter, or even an RTS. But I'd settle for an army that does its own thing.
Alchemy: Liked the feel of potions in The Witcher (much longer durations, but had a "toxicity" concept that prevented you from using too many at once). The oils there were much more useful than poisons in Oblivion, and bombs would be a nice addition. The requirement for potent Bases and numerous reagents for powerful potions would be another useful balancing tool. However, it didn't have the flexibility of creating your own potions, which would have to be addressed. Liked the Research concept from BS2, and think something similar (involving combining ingredients rather than damaging enemies) would be great for Alchemy.
Armorer: Would be nice to see it extend to weapon creation or modification. The "simulated" forging sequences in Dark Messiah (and Ultima 7, I suppose) were pretty neat, but lots of games have decent craft systems.
Quests: Daggerfall's random quest system would be nice; not for important quests, but more as a way to earn money and skill through your guild without aimlessly wandering around. That is, as way to be a full time Fighter, Thief, Assassin, Gladiator, etc. Hunting bounties, guarding caravans, assassinations, gladiatorial fights, chariot races, courier deliveries, targeted burglaries, all fairly straightforward repeatable quests. Mages aren't well represented, but research could be sort of a freeform quest system for them, if ingredients tended to be found in specific remote locations. Also, mages could have "country doctor" style quests for alchemists and restoration specialists. I suppose enchanters could also have "quests" that require them to create specific enchanted items for NPCs (that would typically be useless to PCs -- an Enchanted Broom of Sweeping sort of scenario).