It may not be that hard to set up things for yourself, have been toying with something like that for messaging https://cweb.gitlab.io/StoneAge.html. The deeper question is how to sustain this kind of products and make them competitive without comparable funding.
What if everyone had a personal always-on cloud storage like dropbox, or even their ISP, where data is encrypted and access managed via crypto keys exchanged directly between clients so that plaintext never leaves the client. This gets us around devices being offline and NATs. Clients communicate via these always-on cloud stores using them as store and forward network, along the lines of http://cweb-services.com/intro.html
There are challenges like establishing initial connections, or push notifications, but these can hopefully be worked out.
Intermediary is not the best word here. What if you could use a storage infrastructure to implemented a protocol for storing and retrieving packets across NAT and disconnected devices. If the role of storage is similar to the raw networks transport via ISP, then it is not more centralized than using an ISP.
