I was watching the Matthew Garret "Heresies" talk from Debconf17 today. The following thought struck me:

True software freedom for this age: you can get the source code of a service you use, and can set it up on your own server. You can also get all your data from the service, and migrate it to another service (hosted by you or someone else). Futher, all of this needs to be easy, fast, and cheap enough to be feasible, and there can't be "network effects" that lock you into a specific service instance.

I will need to think hard what this means for my future projects.