Following on from the "Are the Tau screwed" thread, I think the Tau may be the race destined to bring down the Imperium.

My evidence; the Enslaver plague wiped out the Ork "Brain Boyz". The Nids and Orks wiped out the Squats. Slaanesh and the encroaching Imperial Empire disected the Eldar Empire.

So, tehrefore, are the Tau, another fledgling Empire, going to bring down the Imperium? Obviously not in the near future of course.