Free Nostr relays will not survive because they don't have a business model. Except that many services like https://www.freelists.org/ exist since at least 1999.
In 1999, the web worked very well with servers hosted from people's basement. I think if you got a start there, evolving your server infrastructure over time in a financially sustainable way was possible. Now the web demands speed and availability. It seems like nostr relays are especially demanding for speed. Residential ISPs have made it difficult to run personal servers in-house, but perhaps taking a free relay straight to cloud infra is the expensive and unsustainable path.
The fediverse has survived and grown off free servers for a decade. And when a fediverse server goes down it's worse than with a nostr relay goes down.
@[NPC] Tony - this is the thing you were fixing right?
Uh maybe, i think it's about finding an easy to replicate model which is balanced between cost/load efficiency, with a tiny positive net production. Like maybe the author is asking about the solarpanel-counterpart for a nostr-relay? Tbh, I'm not sure I understand the question.