Go is basically Limbo combined with Oberon-2 method syntax, two very successful programming languages from Bell Labs and ETHZ respectively, hence why Go was such a guaranteed success.
First, combining two successful languages in no way guarantees success. (Imagine combining Lisp with C++ syntax.) There are lots of ways to do it where the whole is less than either of the parts.
Second, you seem to have a strange definition of "success". Limbo was a success? Well, some people used it, and some software got written in it, and some people used the software. Not much software and not many people, though, in the grand scheme of things. Same with Oberon-2. Even if you consider those two languages to have been successes, Go is a far greater success - it's successful in a way that neither Limbo nor Oberon-2 ever were.
Ah, I see. Sarcasm often doesn't come across in a post. But yes, I was surprised by your post, because it didn't sound like your usual position. I should have suspected sarcasm.
But I disagree with you. Bell Labs was adequate branding for C and Unix, but not for Limbo or Plan 9. Sun's branding (and relentless support) was necessary for Java, but who did the same for Python, Perl, or Ruby?
It's not just the branding or the marketing. Sooner or later, how well the language enables you to write programs has an effect on language popularity and uptake.
Programmers aren't just fashion-driven sheep led around by marketing departments. They actually use the languages, and they can in fact tell when the language makes things easier or harder.
Second, you seem to have a strange definition of "success". Limbo was a success? Well, some people used it, and some software got written in it, and some people used the software. Not much software and not many people, though, in the grand scheme of things. Same with Oberon-2. Even if you consider those two languages to have been successes, Go is a far greater success - it's successful in a way that neither Limbo nor Oberon-2 ever were.