Then why not make the license AGPLv3-or-later, to avoid other people creating proprietary forks? I get that it's not a common occurence within the Golang world, but nothing will change unless more Golang projects start making their code copylefted.
Proprietary forks are OK with us. It will be too expensive to maintain branches of their own and catch up with the upstream.
Haha, you guys are awesome! You've totally figured it out. Stay awesome!