I think that we need a little more diversity.
For me, Skyrim has a uniformal makeup which has become a trend in the titles and most RPGs and without adding more content in this regard it becomes boring after awhile.
Without verging on technicality and sophistication I won't mention actual changes to gameplay and stuff like that. Instead we need to see more diversity in guilds, heroes, weapons, apparel, the inclusion of more NPCs. A diversity of behavioral relations NPCs have towards you or to each other and they need to shift based on the randomization of the NPC's actions and the effects of those actions on other NPC's. The AI needs to be supplemented and needs to be injected with more data and needs to have the capacity to support a psychological database of human interactions so as to create a vibrant world, one that's reflective on a realistic scale of the one we live in, keeping with that time and era. It has that potential. Skyrim is in the light of that early dawn where AI requires diversity of behavioral differences that mirrors human psychology. It's imperative with the way this game and other games are going. It's a fundamental requirement for it's evolution. The technicality, I think, is considerably behind the times. They can do much better. But rather ignore the pickiness of the players, it is like that because now we open a corporate door. And whilst opening this door there is that gloomy shadow of speculation and business interests. For the purpose of this topic, I will keep that door closed.
The most important thing above all is level of activity... We need more NPC drama and more of them selling buying and living in the game. I think this waves a magical wand over a dead flower bed and fills it lush vegetation. It needs to be more busy.
The ability to join more factions/guilds
Necromancers
Foresworn (Some might enjoy this)
Bandits (Get hired in a posy)
Highwaymen
Traders guild (a bit like the khajiit caravans, but you make and sell stuff like them.)
The ability to create your own faction.
The ability to become a lord of land and capture strongholds.
The ability to declare war on other factions or join their sides.
More rivalries (Like guild against guild)
Just some stuff, there lots more but I think this touches on the imperatives.
Overall, we might see the sophistication of gameplay and abilities increase in up coming titles.