I really hope that the Dregs isn't using the same point system we see in the Faction Campaigns. I'd like to see the Dregs base its victory condition on map control. The question then becomes: How do you prevent latecomers from spoiling the campaign by waiting for Winter to make their move and conquer the map? I'm sure this question is easy to answer, and the use of player built cities and the bane system for sieges/war declarations will mitigate this greatly.
The Dregs will have a vastly different "feel" than what exists currently in the faction campaigns and should correspondingly have a different system for declaring victory. I like the idea of a leaderboard where you're guild is only able to get on it if you meet certain conditions (owning a large enough city/stronghold, owning multiple cities/strongholds). Once the qualifier is established, the guilds on the list must either eliminate each other or force each other to "bend the knee", abdicating the campaign victory to another guild on the list. This also differentiates players and guilds who are "playing to win" from players and guilds who are just there for their own reasons (crafting, PvE, ganking, etc...) When you include the ability of guilds to band together and make their own "factions" (and break them up when things don't work out) there is the potential for different reward schemes based on player/guild/alliance status.