RFC 5549 - IPv4 Routes with IPv6 next-hop - Does it really exists?

Let's just jump all the arguing about lack of IPv4, the need of IPv6, and etc... I must confess that I don't know all the RFCs. I would like it, but I don't! And today, I reached on https://tools.ietf.org/html/rfc5549 I knew that was possible to transfer v4 routes over v6 BGP sessions, or v6 routes over v4 BGP sessions. But I got surprised when I saw this youtube vídeo of AMS-IX guys considering use a v6 only Lan, and doing v6 next-hops to v4 routes. https://www.youtube.com/watch?v=uJOtfiHDCMw Well... I guess that idea didn't go to production. But the questions are: There is any network that really implements RFC5549? Can anyone share some information about it? -- Douglas Fernando Fischer Engº de Controle e Automação