Something that I seemed to really catch onto now that I've really started thinking about the fact that the class system was removed was exactly how the AI will function. Now, obvious AI is the hardest thing for a game to get right and Bethesda games are especially infamous for the ways the AI is incorporated in combat. In Oblivion I found that it was an all or nothing approach, with those that could cast spells using them whenever they could but instead of making for cover whilst they recharge they go ahead and melee you thus leaving their squishy faces open to a Daedra mace. With Skyrim coming around we can obviously expect upgrades in AI, but exactly how will this be done?

One thing I suspect might be the case is regarding the Tool set used for all this. Obviously when creating an NPC you give them their abilities and equipment, but perhaps there is another option that states their fighting style. I wouldn't expect anything huge, but I definitely think that a mage fights different from a ranger and that a warrior fights different then a rogue. I of course try to keep my expectations low when speculating, but I do believe that with these new additions to combat like the dual-wielding and the finishers there will be ways for NPCs to reflect these in new ways of combat other than spam range and then go to melee.

there are fighting styles in Oblivion and I believe Morrowind

Thats a great idea! so may be have a class system for NPC's but not for the character?

Well, they weren't too evident. As I said, the ranged attackers will range until they run out of mana or arrows and then they will go and try to melee you. It also sort of complicates things when you regard that arrows are far more rare in Skyrim and thus using them in a blitz without recollecting them if possible would seems a bit strange. Also, there is absolutely zero difference between an assassin-like character and a Warrior type if they're all ready fighting.