Nostr adoption is certainly growing, but it will eventually hit a plateau, as the UX is still very inaccessible to normal users. The problem isn't getting them out of their existing app. It's about an unfamiliar UX. Most Twitter users (who did switch) switched to Mastodon and Bluesky, both have a similar UX to Twitter (on Mastodon, as long as you stay on mstdn.social).