At the moment I dont see any competition between guilds. Game is very close to single player, how about:
-Then developers bring pvp into game, they could bring guild pvp aspect too ? Guild vs Guild to take or defend some object ?
-Economic competition to complete something massive before others, later to defend or take it from others (pvp) ?
It would bring more social aspect of bigger groups into game, imo that would be nice and fun.
Sorry for poor English