In Oblivion (and Morrowind especially) your fellow faction members never seemed to do anything for the faction and never progressed in the faction. What I would like to see in Skyrim (and what Bethesda might have already done) is to see faction members actually do something. In Oblivion/Morrowind, they would just to their daily scripted schedule within their cell, which was nothing. They never did jobs for the guild, never reported to superiors, and never advanced in rank. It would be nice to see other guild-mates go out on a randomly scripted assignment and after doing a few quests, actually advance in their rank. Of course they'd have to stop advancing at some point because the game is made for you to become leader of most factions. Come to think of it they could make a quest line out of that. You and another guild-mate competing for the guildmaster's favor and achievement in new rank. From what they discussed so far about Skyrim, this isn't too far fetched.