I know that Bobik had announced that there will be little to no NPC's in the traditional sense of RPG's. But having said that, there are a few problems that I forsee arising from this arrangement:
1. Droll tasks will become time sinks that will eventually discourage players
2. It's NOT fun deciding strategically when having to decide to do "work" or "play." (It should be play all the time, or work should be play)
3. PC's are not persistent in the world, and having no NPC's to "mark the spot" makes it difficult to have an sort of persistence.
So, the solution? Put in player created NPC's that are stand-ins for them. This like the Spartan system of society. Essentially, you have a lower class of peoples who support the work of the elite (in this case PC's). This would be the laboring class that is created. This is just a physical representation of the PC's influence on the world. For example, in a territory controlled by Lord Farquat, Lord Farquat will have his laborers dig stuff out of the ground.
I also advocate putting strict limits on the use of such NPC's. The NPC's should be limited in ability and scope. High HP, but dumb. They are also a money sink. (Gotta pay the laborers in living wages.)
In the example above of mining, the Lord would need a surveyor who would mark the territory, and only then will the mining laborer be able to excavate resources out of the ground. To stop excavation, another player would just have to whittle down the NPC's life.
Why would we do it this way? There are several advantages.
1. It solves the problems I posed previously.
2. It opens up new potential for raiding. Stop resources by killing NPC's. Or defending NPC's. They are going to be tied to local areas.
3. Provides a context by which to classify the player base (ie, at least PC's know they're a step up beyond the laborers.) And this is true to the feel of the Medieval era; someone needs to be the serf; NPC's provide the lowest class.
We can all agree that there are repetative tasks we would rather avoid. Also, no one wants to be that lowest rung in the Fuedal chain. NPC's provide an easy out that proves true to the theme and feel of the era. NPC's are like the unwashed masses that are the serfs of medieval times. Expendable, abundant, not very bright, but a useful resource.
Player created NPC's are going to be a wonderful addition, if applied in small amounts, and judicially.