If it's not a damn algorithm threatening your business it's any myriad changes, take your pick. Start with the changing face of the Internet where blogs ruled for a time. That's passed. Social Networking sites arose allowing self-expression in closed systems, some of them withered (MySpace). Now people are connecting with each other over Facebook and to an unknown extent on Twitter.
The current disruption is the change from the computer to the hand-held mobile devices, which itself is still in transition. Some sites that rely on at-home/at-work visitors are losing traffic and the acquisition rate of new visitors is declining, particularly if their sites break on mobile devices.
HTML5 is not only changing the face of how the web is accessed but changing what the web is, what a site is or is not.
All of these changes are destructive but they are also opportunities. Is Panda an opportunity? Yes, no doubt for those that are pushed up. And like all other changes, it's a nudge or kick in the pants for someone else.
Back in April 2006 I posted this:
[edited by: martinibuster at 7:07 pm (utc) on Oct 21, 2011]