I'd love the capability to make Persistent Worlds, but it does seem out of scope. Perhaps, just maybe, they'll have enough editable functionality to allow modders to try for this. But it would be unwise to focus too much attention on these for an admittedly low-population game type.
And I agree with Horrorscope. VERY important that a GM does not have to be where the players are. This would inherently mean that combat (and some dialogue) can be automated. BUT, I really believe a GM can take over any NPC. Generic monster, enemy boss, random NPC villager. They should be able to chat as that person. Additionally, there should be some robust 'rolling' mechanics for non-combat skills (or, at least, some basic functionality that a GM can extrapolate and implement with other game features).