I'm working with S0mebody on some similar ideas for Novum Mundus, though more centred around gold income for factions with all gold going to a central chest, which may not actually be on the same map as certain castles (e.g. Money will go from sparsely populated maps to the core maps with the cities on them); this is mostly due to the persistent factions feature I'm adding, so I don't want factions being wiped out, only subdued. Obviously what I'm doing is heavily reliant on databases, so it isn't possible for anyone other than myself to host servers with these features on NM.
Though what we're working on is centred around multiple connected servers, your ideas are centred around a single map, so it'd be interesting to see how it works out though, but I feel having such features on a single warband map would makes things... Cramped? But yeah, I like system.