Great points! I think we'll see some of those new apps / use cases pretty soon. Your idea to earmark a percentage of donations for relay operators is a good one. I'd love to see experimentation there. I also hope (and expect) we'll see several well funded companies enter that can eat those costs for as long as necessary until the economies of scale kick in.
Discussion
New companies coming in and using nostr is indeed a great growth vector, you are right.
I also think that even slow growth is OK.
By 2027 it is predicted that AGI will come in and you will have robots with autonomous intelligence. Nostr will a great environment for them to interact, and make rapid progress, rather than the incremental we are seeing now.
So if nostr survives a few years, it can take advantage of cutting-edge new collaborative systems of humans and machines working together.
Plenty to be optimistic about, but important to remember that short term growth requires infrastructure. I would much rather think about a path to 100k WAU, than 1M. Because, unlike bluesky and mastodon, nostr does not have the capacity for 1M users. It may be easier to think of growing it in stages of capacity and users together.