Go doesn't address concurrency design deficiencies of C++ in any way, while Rust does. So I don't see Go as a next generation successor, but Rust really looks that way.

I like C++ personally for its power and keeping performance accessible (especially with new developments of C++11 and beyond). And looking at new alternatives, Rust looks more like a successor to me than Go. As others pointed out, Rust doesn't enforce garbage collection, while Go does. For example if someone would want to write a demanding game, they wouldn't do it with garbage collection enforced language.