Go was never intended to be a C/C++ successor, it was intended to solve a class of problems that Pike and gang experienced in the software they worked on. Which is to say network servers. What you are probably remembering is that they assumed from their unique Google lens that it was C++ developers who had those same problems and would see it as an alternative to C++ when faced with those problems, but it turned out that in the "real" world people were writing network servers in Python and Ruby, not C++.
Which isn't surprising to the rest of us. If you remember the days before Go, every second thread on HN was about how "company X", including the company now known as X, saw their Ruby network servers completely falling down under load, forcing a rewrite in whatever the language du-jour was that day. But Googlers tend to live in a completely different bubble with respect to the way software is written.
Well, a lot of servers are Google are (or were) written in Java not C++. As a GCd language, arguably Go competed with Java internally moreso than C++. One of Go's flagship projects (Kubernetes) started out being written in Java for example.
If I remember the legend correctly, the idea for Go was initially conceived while waiting for a C++ program to compile. Not sure about any of the other stuff, but they definitely got the compile times right...
Which isn't surprising to the rest of us. If you remember the days before Go, every second thread on HN was about how "company X", including the company now known as X, saw their Ruby network servers completely falling down under load, forcing a rewrite in whatever the language du-jour was that day. But Googlers tend to live in a completely different bubble with respect to the way software is written.