There's still too much story to tell in the series for them to quit now:-Cantha is an entire new region to work with that could be integrated with the next expansion-The mystery of the sea dragon is completely untold. We don't even know its full name yet. We also have to face the effects of upsetting the balance of magic by killing some of the elder dragons, along with what chaos Kralky has inflicted on the mists. Also, Primordus and Jormag are not dead, they are just dormant. Who knows when they will next wake, but their inevitable threat should not be forgotten.-Speaking of, all sorts of additional threats may be found in the mists. Kralkatorrik's bungling through it may have put Tyria's blip on the radar of larger threats than any elder dragon.-The threat of the elder dragons was enough to get the races and organizations of Tyria to work together, however reluctantly. Without a prime threat to keep them that way, divisions could once again drive a wedge between factions. We could be looking at the dawning of.....the 2nd Guild Wars.