> One of the main reasons to stick with C++ (and C) is that the investment you put in the code you're writing right now, no matter how fugly it is, will be there and keep working in the future.

Except slowly people will be writing parts of it in Rust, or they would be using libraries written in Rust (because availability), and then after a while people get annoyed of using more than one language and the whole project will be rewritten in Rust. Of course, at that point, a new language will be invented and Rust code will be looked at as rusty :)