> the public sphere (a problematic construct to begin with)
What's wrong with the public sphere as a construct?
> On what new basis solidarity
> could be rebuilt is entirely unclear to me.
Things sure look bad at the moment, but I think it will come back, we humans have it in us, we always had, we just got distracted and temporarily forgot about it. It will come back to us. Solidarity does not need to be built, it will grow like vegetation coming up in cracks in the asphalt.