I think we all know with the recent influx of players from the steam sale, and most asking to be let into alliances, I think its sorely time for an alliance upgrade (once everything else is fixed first obviously)
What I would love to see, is possibly a shogun 2 influence system for the map, alliances battle random pvp matches in their selected region and every victory gains them a certain amount of influence, and losing gains half of it, so there is benefit to everyone battling (besides the crowns).
Now once an alliance gains a certain amount of influence in said region, they take it under their control and are able to control the tax rates in that region, to help buff or slaughter the local populace, the capital of each region shall be the alliance stronghold and would need to be fought over once another alliance has more influence in that region.
For example, if another alliance (A) take the region through influence and the owner alliance (B) keeps trying to pay them off, alliance A can change the tax rates through force of trade and basically starve the owner alliance out of the stronghold forcing a land battle between a set number of players, if they decide to attack the stronghold each alliance must select a set number of players to fight for it (say 5 for example on each side).
Not only will this enlarge the pvp scale of things, but also make alliances more useful rather than having another chat tag.