Matrix.org is a start.
On a much much broader scale the Web 3.0 will be build on Blockchains, the so called Fat protocols will surpass the Web 2.0 or eventually merge.
https://www.usv.com/blog/fat-protocols
Ethereum will build up a considerable part of the ecosystem, with Dapps like status.im
https://m.youtube.com/watch?v=Je7yErjEVt4