In terms of third party code built in the same language, perhaps. Calling C is pretty straight-forward in Go (http://golang.org/doc/articles/c_go_cgo.html) and there are starting to be more and more 'native' libraries available (http://go-lang.cat-v.org/pure-go-libs for some, but by no means all).

So perhaps it is more of a sacrifice that is getting smaller day by day?

Why is it necessary to 'switch' at all? Can you only hold one language in your head at once?

I wasn't distinguishing between switching completely and switching just a part of the infrastructure to go, for brevity's sake.