Skills: Rather than reducing the amount of skills available I'd much rather have them (more roleplaying!) and make them more interesting.
Acrobatics: I'd love to see climbing. If only just being able to grab onto, hang onto, and sidle along ledges. You could go from being able to grab onto and pull yourself onto ledges, to moving along them while hanging, to being able to jump again while hanging onto one.
I'd also love to see dodging. Jump button + direction that's not forward = dodge that way.
Hand to hand: How about as you level up you acquire different styles. You equip them like weapons, getting styles that are very fast, one concentrated on knocking enemies back/off balance, etc.
Mercantile: The higher you get mercantile the bigger your rewards for completing quests! That and have it govern bribes. I didn't like bribes just being a “get the npc's number higher” but you could bribe an npc not to report a crime. Or bribe a corrupt guard not to arrest you.
Perks in general: I'd love to see perks become something like talent trees. You have to unlock lower level perks to get higher level ones, and there would be minimum skill and/or attribute requirements, rising the higher the level the perk is. This would help differentiate players even more, an enjoyable thing for both roleplayers and min/maxers.
I also don't like how a lot of the perks sound. “A perk that allows a mace to ignore armor” sounds like it won't affect how the game plays much. Might as well just say “you do more damage with a mace” for the most part. Perks, even if there are a lot less of them, might be more interesting if they concentrated on making the game play differently when you get them. “Adds a power (press and hold) swing to your mace. Takes longer but has a high chance of knocking the enemy off balance.” Then you'd have more to consider, when fighting, rather than just a higher number.
Combat:
Magic actually sounds good so far. But I'd like to see destruction even more differentiated, with lightning being nigh instantaneous and have the ability to chain to nearby enemies. Fire a medium speed and be able to knock down enemies (exploding fireball), and ice to be the slowest but most powerful (as well as slowing enemies).
I'd also love to see a really good dispel... spell. Someone casting a fireball at you? Cast a powerful dispel fast enough and it disappears, same goes for trap spells and summoned creatures.
As for ranged. Team Fortress 2 has simply the best bow and arrow system in any game I've ever played IMO. I support the higher damage arrows, but require some timing too. Your shot should be the most accurate the instant you knock the arrow, and slowly start to lose accuracy the longer you hold it. It works incredibly well.
Finally there's melee combat, and this is what I'm most concerned about. “Visceral” is not a good watchword. Having the combat look violent and cool does not actually make a good game, that's just the icing on the top of what's ideally a delicious fighting system cake. I should just link what a designer wrote about Street Fighter, regarded by many as the most satisfying fighting series in the world.
But the basic idea is giving the player several options at any one time, with only a split second to decide which one is the best. A troll swings normally, blocking or swinging yourself might be the best depending on your respective health meters. A troll charges, dodging out of the way is the best, as standing in it's way will get you damaged and knocked down. Point is, I'd really like to see more talk and concentration on the tactical decisions you make, i.e. the actual fighting system, and less on the “kill moves!” i.e. what makes it cool to watch other people play the game.
Graphics: The interiors are going to look flat. I love reading about realtime graphics, and not stuff like that “Graphics of Skyrim” GI article. But the research papers guys publish that are filled with trig equations and make a lot of programmers twitch from sheer complexity.
The interiors are going to look flat, because there are once again going to be maybe two or three lights, and I don't see any ambient occlusion so far. A deffered shading model allows for hundreds of lights. That popular “real lights” Oblivion mod could be outdone by the designers, with (time appropriate) light streaming in from every window, showing off from every candle, and glowing down the corridors with every fireball. That and it sets up a lot of the stuff necessary for SSAO, which for those who don't know is a wonderful looking technique. First used in Crysis, it makes the lighting look a lot less flat by giving everything a soft “very close” shadow.
As for seeing outside, a single modder, the famous Reneer, is currently creating a mod that allows just that for Oblivion. If a single guy can do such for a 5 year old game I see no reason a large 150+ company can't match it for a new game. I'd suggest a hand placed point for each building that acts a “camera point” for each interior. When you stare out the windows the game shows whatever the point can see from that perspective (minus the building your in). I'm sure there's probably a better way to do it, but I'm also sure that if the game can handle all the exteriors it can handle a single extra interior at the same time as well.
I'd also love to a bit of extra stuff for the pc.
Anyway, a single person working on such should be more than capable of adding some extra stuff. Tessellation for much higher poly models is very cool. That and better shadows and lighting, specifically very cool DX10 godrays (that don't shift around a lot depending on how you look at them) and realistic shadows (PCSS, the farther away from the caster they are the softer they are, same as in real life). That's just three things.
Well, that's all I got. I'm sure you guys have a lot more though. Play nice! Try to offer constructive criticism instead of “I don't want that because I wouldn't use it.” And remember, your the customer! It's your fifty to sixty dollars, that buys you at least the right to come up with your own ideas. And we can all hope that after Oblivion Bethesda has realized their fans are on the rare occasion perfectly right about stuff; even if they haven't played it yet (level scaling, culling, enchanting not being a skill, etc.)