Randomly giving away the guild isn't really 'a chance to complete'. They could make it like Rag, where it gets harder to hold a guild for too many days in a row (with a power handicap for each day), but even this will just result in two guilds passing cities back and forth. They should try to give smaller guilds a chance to improve, but this suggestion doesn't really help (but I don't have any better ideas on what can help).