I'm seeing some serious issues with this idea, at least as far as the implementation has been laid out here. Let me lead in with my understanding of how you guys are suggesting making the game, so if I got something wrong you can address that instead...
It sounds like what you're shooting for is a game with Region vs. Region [RvR] combat handled primarily by NPC armies (possibly simulated battles rather than actual in-game ones) commanded by noble PCs. Nobles also build buildings and such, kind of like in a 4X game. At the same time, you want commoner PCs who somehow influence how these battles go, maybe, in some indirect manner relating to meta resources. Except rangers, who will apparently be doing attacks on NPC encampments.
The problem is there's too much division between incompatible parts. You've got the nobles, who it sounds like won't have anything to do when they aren't issuing orders to NPCs. The only thing they can do with non-noble PCs is slow them down, since the commoner PCs would basically have to stop what they were doing to interact with nobles. You've got PCs who really can only interact with each other, with some of them able to risk getting killed by massive groups of NPCs. What they can do with each other is a mystery, since there's such a huge divide between commanding huge NPC groups and pretty much any other aspect of gameplay. Now you're thinking of adding neutral areas, which will probably draw away a lot of PCs who don't want to get murdered by large groups of NPCs.
You're basically creating a minimum of 3 PC cultures that have no motivation to interact beyond RP flavor. Plus, there's very little chance you will have enough players to support this thing out of the door, so there's going to be a lot of nothing happening.
That's my understanding of it. On to alternatives...
Those are fair points. I think by having NPC units be the background flavor and 'consequence' of actions that Noble PCs make, and by not having them 'targetable' or able to target PCs, you remove the worry of insta-gib Death Squads roaming the landscape, making short work of any and all PCs in their path.
My idea is (personally) to make all the PCs slightly above the 'bottom dregs'. While you could certainly play a nobody beggar or a farmer or a mercenary, it'd be cool to start off in the game with control over a small group of NPCs. Instead of working yourself up for grueling months to a point where you can open a shop, start a PC and have a shop with an NPC shopkeeper as an instance (so it loads around your PC, and if you don't log in or if you die, the shop closes). Allow 'rangers' to be free form fighting men/women, with the detailed things Orin put above, and have them be more of the 'Solo PvE Class'. Have soldiers start as Corporals or 'slightly higher than Private', giving them a few NPCs to put under their wing.
One could argue that Nobles in any sort of game setting don't have anything to do if they aren't ordering NPCs around -- But this is where the RPI aspect comes in. As masters of their hold, they can/will interact with their populace, and the other PCs under them/around them. Just as in any RPI, you have to make your own fun with plots and story, and not rely purely on code to do the work for you (and rarely Staff, in my personal opinion).
Neutral areas (again IMHO) could be opened or closed when 'scenarios' are merged. So they aren't free for all gain for anyone -- Unaffiliated people could squat in them / trade in outposts, but not 'conquer' the territory in the same way affiliated House members could.
RvR - Throw out NPC armies as an idea. The only thing they'll do is afford the playerbase something to get pointlessly killed by if they do anything but watch. Instead, these forces will be a constant simulation going on for all sides in all locations. Something going on in the background everywhere. Nobles will have indirect command over these armies unless they were physically in contact with them. Otherwise, all communication would be done using messages; these are physical objects that have to be transported and can be read/altered by literate PCs. Nobles will use these set how much training is going on, how aggressive they should be, where they should be concentrating their forces, as well as receive information back about what is going on. The catch is, the armies may not be able to follow commands; things may escalate unexpectedly, they may not get the orders relayed, etc. Major battles could result without opposing nobles even meaning for them to happen.
While this all is going on, it should influence regions indirectly in ways the playerbase cannot escape feeling. If a side loses territory, it could cause anything from food shortages to increased costs for leather goods to an easier atmosphere for raiders to operate in. Winning battles might cause an influx of resources or swag. That kind of thing. Players should have social/environmental commands that allow them to figure out what the situation is in a civilized area based on how long they've been there.
Areas these simulated forces are fighting in should drop descriptions in neighboring areas and leave behind items, bodies, etc.
I agree with some of this, but I think the NPC army units are a neat idea (or just giving more control of NPC units/NPCs to PCs in general, pitted against each other). Removing the ability for ordered NPCs to attack PCs still allows PCs to come into conflict with each other (with their NPCs) -- They simply can't order NPCs to kill a PC, and roaming death squads wouldn't happen/be possible codedly.
In my divergent mind, the 'neutral' territory (once open) would look a bit like a chess board. Each day (or less, depending), Nobles from each side could assign NPC units to different quadrants within the neutral territory. If/when the NPC units come into conflict with each other, they clash until one side is dead or the NPC unit flees. PCs can attack each other in these rooms as well -- And PC deaths within the rooms would sway an NPC unit to win or lose.
Nobles - In addition to sending orders to forces afield, they manage areas they are in. Mainly this is by setting buildings to be built/demolished, but cannot build them. Buildings will be built slowly by VNPCs, or more quickly by PCs either working on them or bringing resources to the sites. They would also have command over the NPC guards in their areas, control the crimcode, that kind of thing. Nobles would still need to involve themselves with combat PCs as well, for dealing with raiders (you could allow PCs to handle this, or autogenerate NPCs when there are not enough PCs doing it), and for making their way to conquered areas to coordinate rebuilding.
Only problem is you'd have to come up with something if you want nobles to be able to travel with forces or if you really wanted them involved in a battle. Maybe just have a staffer around to spawn NPCs for when room echoes aren't enough?
I like all these ideas. I think a Noble should be able to go with/do what they want within reason. It's very within the IP to get killed for making stupid mistakes, like going on a hunting trip while you're at war and getting killed in an ambush.
Commoners - Mainly take the place of NPCs/VNPCs who are less effective at doing everything. PCs would deliver messages between nobles and their forces, gather resources, scout, raid, etc. One of the few roles that would be PC-only would be spies. This would both be directly from interacting with other PCs and indirectly, though staying in an area and using the social/envornmental observation commands to gather information. They could (obviously) join the other side, in addition to intercepting messages and/or altering their contents.
Like the nobles, the only thing I haven't worked out is how they'd participate in large-scale conflicts directly.
I think there's a way of making the 'macro' battle happen on a scale with NPC to NPC combat, where the NPCs can be either better equipped, have better stats through bonuses applied by the Noble's House, and a degree of luck. NPC units / forces arrive and clash with one another, fleeing, taking up positions elsewhere. Single NPCs can and will target PCs, but will not be of a power (by themselves) to slay a PC. A group of single NPCs though would be problematic.
PCs can be involved in the combat, but only against other PCs and single NPCs. There would need to be some kind of mechanic where only 1-3 people can engage each other at a time, avoiding pile-ups of NPCs and also of PCs. Depending either on a skill or something like that (so a talented swordsman could engage up to three opponents at a time for a brief period before succumbing to exhaustion, while a not-so-talented swordsman would be overwhelmed by two from the get go).
Large scale combat isn't something i've seen successfully accomplished in MUDs -- I'd be curious to see what safeguards/skills/ideas could be applied to a scenario to make it fun to watch (NPCs vs NPCs) and also fun/thrilling to participate in. Most of what i've seen are spam fests where your PC and other PCs die before you can get through the screen scroll. That'd be something that would need addressing from the get.