I'm unclear from reading your comment if you know this or not... but, what the Go team is describing is an intermediate solution. Not the exact one you describe, but it is intermediate. There is no particular requirement to get into the Go package ecosystem, no gatekeepers, it's all namespaced by the URLs you store your source code at, but between what the proxies do and the way the version requirements were specified, you are also not simply naked to every update someone somewhere pushes.

Please note I'm not claiming it's perfect or that you'll like every aspect of it, I'm just saying it is an intermediate solution between the two extremes.