Go offers nothing for C programmers, and Java/C++ programmers are largely using languages by corporate decree, not choice. Go's main audience is in fact people who are still clinging to dynamically typed languages. Where modern languages like haskell or scala are too scary for them, go is familiar enough to draw them in, and show them that static typing doesn't mean java.
'clinging to dynamically typed languages' and 'too scary' implies that the only people using such languages are incompetent beginners. That is posturing more than it is an honest description of reality. Same applies to your description of Go as nothing more than a bridge to Scala.
Are you so sure that everyone using languages other than Scala and Haskell is that much dumber than you are?
It took a while for C++ and then for Java to become languages of corporate decree. If Go will ever become one of those languages, it will take around the same amount of time.
As someone who only used C for systems work for 15 years, and for the last two years switched exclusively to Go (except in the kernel) I disagree. Go offers everything I want as a C programmer.
I didn't mean to suggest that absolutely zero C programmers would adopt go, merely that go does not address the needs C does, so most people using C won't have the option of using go instead. Obviously if you were using C for things that didn't need C to begin with, then go becomes an option.