As of sometime yesterday (August 16, 2017), syncthing is available for installation from the official fedora repositories. For now, the package is still in the
updates-testing repositories for fedora 25 and 26, but it will probably enter the stable repositories in 6-7 days.
Update (August 19, 2017)
In the meantime, my syncthing-gtk package has also been approved, and it too will soon be available from the official fedora repositories.
Update (August 21, 2017)
As of today, the syncthing-inotify package is now also available from the official fedora (f25+) repositories (or it soon will be).
Update (August 24, 2017)
It looks like syncthing (or one of its dependencies) is not yet fully compatible with the coming golang 1.9 release, which leads to crashes on fedora 27 and rawhide. I will investigate further and hope that this can be resolved soon.
I would like to thank Jan (jchaloup) for getting me started in golang packaging for fedora and a few package reviews, and especially Athos (athoscr) for doing most of the package reviews necessary to get all the dependencies and syncthing itself packaged.