The was a discussion about giving the realm authority objects the need for upkeep. The idea is that if no-one comes by from time to time to feed it something it'll go defunct and can be broken with hand (and without scents), so either the local population does it as it likes the benefits of the realm -or- the rulers will have to organise something as authority objects no longer connected to the coronation stone would also go defunct, so either keep the chain intact or lose whole areas.
Additionally I would suggest a time gate that limits building of the next area extension object, like we have with banners for villages.
This would put an end to endless, zerg and/or tentacle expansion.