There's already more overlap than people probably realise. I used to sh-tpost on Dread before I even heard of Nostr.
Darknet is edgier, but also draws far more heat. If it were to disappear, Nostr and SSB would be next on the list for a lot of State-sponsored bad actors, and IDK how well our relays would handle the level of dDoS that is Tuesday on the Darknet.