I think it's a good idea to speculate about what sorts of things Bethesda does and does not have time to add. That way, we can focus our wish lists to include more features that actually have a chance of being implemented. For instance, I think it's unlikely that Bethesda will implement major combat changes, new weapon types, new mounts, cities, factions, or major quest lines. They probably don't have time. However, they may be able to squeeze in a few new animations, monsters, dungeons, side quests, etc. So, what do you think they might have time to add at this point?
Things that they don't have time for: changes in core game mechanics (because they shift balance within the whole game) - that means no new skills, weapon types or spell types, new major factions (cause it requires not only a great number of quests, but they also have to be cohesive), new dungeon
types (it takes a lot of work from the 3D modellers).
Things that they do have time for: some "new" mechanics that don't alter balance dramatically (f.e. mounts), several new dungeons, one or two new mobs or enemies, spellmaking (it won't make much of a difference if NPC's only use vanilla spells - you won't notice it anyway), subtelties of perks and skills, a few new quest templates for Radiant Story, tweaks to some details of some objectives of the main quest and major faction quests (f.e. change the target from a single bandit to all bandits in the same dungeon).