It's a miscalibration to compare Rust to the complexity of C++. Rust is more complex than Go, absolutely and unequivocally, but that's because Go is hanging out with Lua waaaay out over on the simple side of the spectrum of programming language complexity. Given the enormity of its task, Rust is actually a rather minimal language itself (though there are definitely still a few features that I think could be made simpler).

FWIW, I think it's misplaced to fear that Go will be "overtaken" by Rust. They both excel at different domains, and the systems software that you'd write in one is probably not the systems software that you'd write in the other.