I'm reading a paper by J. Paolillo titled "Conversational" Codeswitching on Usenet and Internet Relay Chat" His description of Usenet and IRC totally qualifies as a futuristic killer of Twitter. But then you see the years of references and remember that these system predicted social media long time ago.
Also the move to synchronous conversation (IRC) from asynchronous (email) could be explained by a speculation that in late 2000s companies needed to access/store lots of data to train their systems. Now there is so much data, that there is no need to store it, training systems on a stream (that is seeing an instance once) is enough. Thus amove to self destroing emails and stories.
The rest of the article is great. I recommend it to everyone on the fediverse, not only to people who are interested in codeswitching. The article is available at http://www.languageatinternet.org/articles/2011/Paolillo The whole journal worth checking as well.
A beta setup of a Mastodon instance primary for family and friends.