Few on Nostr: I am not aware of any POW only relays. However, at some point the community will have ...

I am not aware of any POW only relays. However, at some point the community will have to come up with creative ideas to incentivise relay operators (automatically splitting creator zaps with relays perhaps?). Cutting out relay features to make the operation super cheap is only part of the solution. Quality, full featured relays, which are the kind of relays that popular creators need, require dedication and cost a lot to keep running reliably. Strong incentives will have to eventually be part of the ecosystem for it to keep growing.

Which brings up the following question: Does nostr really need to grow? Nostr could just keep getting better as a protocol over time, and the infrastructure could stay humble, and true to its roots: "It's really all about freedom, not making profits."