What do you mean by "Go has succeeded"? It has found its niche, yes, but so have those HM languages (maybe the Go niche is a bit bigger), and a bunch of other languages that people also like to hate.

Meanwhile, most code is still written in languages like Java, C and PHP.

That's no value judgement or anything, I don't think Java is an amazing language (neither do I think it's a terrible one), but it's not like Go has revolutionised anything. It's just become a new option among many.