Having been around a little while now, I think #nostr could be interesting. It all depends on the ratio of wheat and chaff with these #privacy havens.
It's not always easy to see which way that will go. #TheFreenetProject looked like and amazing idea, but it filled up with really offensive material really fast.
#I2p on the other hand has managed to remain fairly varied and stay worthwhile, albeit still too awkward for #mainsteam use.
I wonder what the deciding factor is?