I would open up their APIs instead. Allow everyone to write their own interoperable frontend or backend. That levels the playing field, allows everyone to compe

I would open up their APIs instead. Allow everyone to write their own interoperable frontend or backend. That levels the playing field, allows everyone to compete on the strength of their interface instead of the size of their captive audience. As you say, the service fills a need (perceived or otherwise). It's the size of the network, not necessarily the service itself, that causes the problem. Make the service a protocol, and move it back into the (web 1.0) fold.