Regardless of what you use for hosting your own stuff, if you want to use a third-party SaaS as a user, they own the data. Want to make a document on Google Docs? That document lives on Google's servers, it's forever tied to their service and mined by them. There's no artifact you can hold on to, other than your user account.

What we need is a system where the data for that Google Docs document lives in a place you control - be it your own hardware, or some hosting you rent somewhere. It's the SaaS that should come to the data, and operate on it there. That way, if you lose your Google Docs account, or decide to edit the document with something else, you actually have that document, in its canonical form. Same for all other SaaS.