I will have a stab at this, for what it's worth.
I'm confused on this point. From what I understand of the design brief, Campaigns are already slated to only last for a certain period of time; something like 3-6 months. Victory Points were only put forward as part of a suggested/potential rule-set. So there might be some Campaigns that are designed to run for the entire 6 months say; factions/guilds/individual players gain points through out this entire period and when it is finished whomever has the most points wins.
This is not to say that this would be the only method, and who is to say how these victory points may be earned. I thought the purpose of these "mini" campaigns was that a wide array of rulesets could be thought up and implemented. So, in one Campaign points may be awarded to how many kills a player attains, in an other; how much of a particular resource is gathered. Even what territory is controlled by whom may impact the number of points earned. I am not suggesting that these are the rulesets that will be enforced; such ideas have been shamelessly stolen by myself from other MMO's/MOBA's etc. I have no experience or practical knowledge of game design.
This is dragging on. Final thought.
Might it be possible to have both finite and infinite resource locations. I mean, like, 3 main locations that are fixed on the map. These churn out a constant, large amount of low-mid level goods/ores etc. This would be good for larger guilds/factions to capitalise on; they can afford to expend the time and resources it would take to sieze and control these locations. It would/could also provide focal PvP areas for smaller, more mobile, guilds or factions. Catching their victims unaware and slaughtering/stealing all that lays before them.
So that's for the larger guilds. But to provide a contrast, as the seasons progress, and the Hunger spreads and the worlds get more torn up, new locations could be revealed. These would provide finite amounts of a particularly valuable or high quality good/ore/whatever. Smaller or more mobile guilds could capitalise on these spots; running in taking it all and then running off again. The random appearence of these locations would also act in their favour.
These locations would also provide further focal points of PvP combat but perhaps on a smaller, more intense, scale. Finally. These locations would provide an incentive, beyond wholesale slaughter, for factions/guilds that might be losing. Even though they are getting less through the Embargo/Vault due to their loss, what they are getting is inherently more valuable. Perhaps this might provide them with the edge in a future campaign.
That's all I got. I might be missing something glaringly obvious so feel free to tear it apart.
I realised I got side tracked by vicotory points and never came to a possible answer regarding time limits. As mentioned earlier in this post;
Victory conditions serve as a means for Campaigns to finish early, their objectives having been completed. In the event that no side has attained a sizeable majority this might occur;
Whatever ramifications this eventuality might have on the other realms/EK would be interesting to speculate on.