I remember fiatjaf mentioning the idea of single location specific relays as well. It's a long way off but it's neat to think about concert or conference venue relays that you could connect to while there or if you have to miss it, you could still see what's going on. It sent me thinking for a long time about what a marketable idea it would be to connect relay access to ticket sales & have a simple app to download that goes along with it. Then, if you're already using nostr, use what lever app you want but if you're not, you'd have a simple, clean, fun introduction.