how many of those have never seen real use/adoption above hobbyists/diehards, though? irc and sms is about it from that list. it was a drag getting people to drop skype for telegram, despite telegram being (in my opinion) more user friendly. getting them to go to something like gnusocial would be damn near impossible.

decentralized youtube might be easier to get rolling, on the other hand. all it takes is sharing your videos through it instead of youtube. think about how most people found youtube -- someone linked them a video, statistically likely to be evolution of dance. no reason that can't be done with peertube.