The rumours about WhatsApp/Matrix federation are very promising, but the suggestion that legal contracts will need signing to federate is worrying. We've done this before, with the traditional telephone network, and we got a cartel.
The first version of Twitter was illegal (or, at least, against telco rules – what's the difference?) because it wasn't "approved" by the telcos. We were only able to launch publicly because of an expensive certification process that skirted the truth.