There's no mention in TFA of the data belonging in any way to the users. And maybe that's accurate.
Yes, we have web/cloud apps now. But that is—or should be—orthogonal to where data is stored and hosted. Of course app vendors have every incentive to create lock-in. And most users are just happy to hear that "you do not need to take any action" and your data will just be magically faster and more secure. But at least around here, wouldn't people rather own their storage? Does remoteStorage have any legs?[0]
This kind of happened with authentication, right? It's common now to use OAuth to provide login using a third party. Of course, they're mostly silos, too, but at least in principle an app could let you choose a provider.
[0] https://tools.ietf.org/html/draft-dejong-remotestorage-07