What the blog post neglected to mention is that you can force module usage, even inside $GOPATH, by setting the environment variable GO111MODULE=on. I have a go command wrapper script called vgo that sets GO111MODULE=on, which I use when I want to use modules inside $GOPATH. More info here: https://github.com/golang/go/wiki/Modules
Keep in mind that contributing to Go requires that you sign a contributor license agreement, something people might not want to go through (no pun intended) for small changes.