It's been a decade since Morrowind and Baldur's Gate and two since Ultima 7 and Ultima Underworld. It's time for something new and dangerous and it's time for a shop with the resources and the expertise, like Bethesda, to take a risk and break the mould again.
The first thing I would do is tell the TES VI team to do nothing else for a month but play X3 Terran Conflict. The reason for this is that every space ship/space station (i.e. NPC) in X3TC is flying around (or not as the case may be) doing it's stuff (trading, pirating, defending, attacking) all the time in real time. The NPCs do not follow scripts to do this, they follow AI algorithms that use real time data gleaned from other NPCs they can "see", recent history and stock "best practice" procedures etc to decide what to do. The result is an incredibly immersive, dynamic and playable game world that is both predictable and unpredictable at the same time. You have to play this game for some time to appreciate that this is so.
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The only issues I had with X3:TC were [1] the very unintuitive interface (took forever to find and figure out the more cryptic commands), [2] the tedium of getting anywhere (even WITH time dilation), and [3] the fact that the scaling was about as all-pervasive as Oblivion's.
On the good side, it had seperate ratings for fighting and for trading, so if you were primarily playing it as a combat game, the difficulty of combat advanced while trading remained fairly simple, and vice versa. The faction interactions were certainly interesting, especially those that happen regardless of whether you're around or not, so some of the situation changes dynamically, while other ships and fleets simply spawn out of nowhere as "needed". It's even more of a niche market game than the earlier TES games, though. I think most players would be bored out of their skulls in under an hour (witness the debate over FT in TES, and this is 10X worse), and an hour is hardly enough time to do a simple trade run or patrol for hostiles. The game goes from a simple "fly your ship here and there" to "in control of a vast space trade empire or mercenary faction", and the longer you play it, the more possibilities open up, if you can deal with it that long. I found it both fascinating and tedious at the same time, and it ate several weeks of my evenings before I put it aside.
Still, the hidden depth and underlying faction interactions make it noteworthy, and the devs here might actually learn something from it (several things, both positive and negative - as in "DON'T DO THIS!!!!").