I'm bullish on the Solid model, but they have a chicken-egg problem. Nobody is going to develop apps until a lot of people have their own pod, and nobody is going to use a pod until there are great apps for accessing their data.

The same thing happened with remoteStorage. There's initially a flurry of proof-of-concept apps, but no commercial quality killer apps to attract daily users.

AFAIK the only cloud storage protocol really used for app development is Google Drive. GDrive got successful by making a great cloud storage solution first, then once everyone had one app developers started making apps for it.