As of now I don't see any problems with C++. I doubt Rust is going to offer something so much better that people will abandon the tools they already have for these benefits. Though, who knows? I never touched Rust.
It just needs a OS company to pick it up and push it down dev throats, like it happened before with C and C++.
If you want the goodies on Windows you need C++, if you want the goodies on iOS and OS X you needed Objective-C and now Swift as well, the goodies on Android require Java, the goodies on consoles moved from C to C++.
Same here, if tomorrow one of those companies decides their SDK should be Language X, anyone that wants a piece of the pie will learn Language X.
This could come from a IoT company that does things well. A company providing unsupervised devices would benefit from a OS with a strong approach to avoiding security bugs.
If you want the goodies on Windows you need C++, if you want the goodies on iOS and OS X you needed Objective-C and now Swift as well, the goodies on Android require Java, the goodies on consoles moved from C to C++.
Same here, if tomorrow one of those companies decides their SDK should be Language X, anyone that wants a piece of the pie will learn Language X.