About year ago I came across interesting thing for learning dynamic routing - educational P2P VPN https://dn42.net/
What if HE.net introduced something similar? Integrate tunnelbroker.net with friend-to-friend network. Users will make virtual connections (tunnel protocol doesn't mind) between each other, HE will suggest in-VPN addresses to avoid collisions. Everything with BGP with private ASNs and private IPv6 addresses. Excellent practice for future ISPs.
HE will have their nodes inside VPN to watch in-VPN BGP routes - users will gain extra points to certification score for more routes.
What if we introduce real tunnelbroker.net tunnel addresses into the VPN? To make pings lower? The only problem is security, then...