Your own timeline is a sigchain — a sequenced list of signed messages. You replicate the content in your network (2 hops away). Bridges between communities can be built or burned. Many islands can exist without needing to erase the others from even existing — mutual separation is possible. Consensus is not necessary.
Is global network culture still possible? If it is, in the midst of the national internets we now live inside of, I suspect it will look something like this. A little different from what we were promised, but maybe a little better too.