So this contraction of services is a bad thing, right?
Wrong. In both cases, there are plenty of alternative solutions. I'm happy to move The Microbiology Video Library from Revver to Blip.tv (although it's going to take me a few days). And I'm delighted that when we are writing AJAX front ends for projects we now only have to cover iGoogle and Netvibes - less work, more concentration of user communities, and potential boosting of the surviving services in a difficult economic climate. Darwin lives!
As I commented on Brian Kelly's blog last week, be pragmatic. Maintain backups. Use the best possible service available but keep alternatives in mind. Plan exit strategies. None of this is new, this has always been best practice with Web2.0 services. Life goes on. But not for Revver or Pageflakes.