C and Java code bases certainly don't look the same. In fact, claiming that about C is simply insulting to the intellect of anyone reading your overenthusiastic message.
I also sincerely doubt that Rust code bases will look the same in ten years. It supports functional and OO paradigms and it's attracting very different classes of programmers. Recently someone wrote a post about difficulties with some OO concepts in Rust, and a top reply said that they never encountered such issues because they program in a functional way.
Go is an exception here, but as soon as they extend the language in a significant way (e.g. templates) differences will start to appear.
C++ doesn't have an idiomatic style because it's used in very different ways by different people. It's impossible to have a fixed style and address the mass market.
I don't think anything in Rust supports OO paradigm. There are instances where people ask for OO paradigm, but so far, there wasn't any movements towards it.
There is no inheritance and no polymorphism based on it. There is generics polymorphism, but nothing like that.
I think you misread a terribly misreadable statement: what he meant wans't that C and Java look the same, he meant that any two C codebases will share a lot of similarity, any two Java codebases will share a lot of similarity and so on. C++ on the other hand can be anything from "C with objects" to deep template metaprogramming to "has there even been a C++ before 2011?" styles, which are as dissimilar from each other as you can get without crossing language borders.
No, there's OO C, low-level C, GLib C, etc. There's Android Java, Enterprise Java, Standard Java. Any language catering to different customers will have various styles.
There are two big C++ coding styles: C with classes, an old style which has little use nowadays and modern C++, the recommended way, used in new projects. Asking "what is the idiomatic style in C++?" must be a rhetorical question, because it's obviously modern C++, the leaders of the C++ community have made this clear repeatedly.
Template metaprogramming is a technique, not a programming style.
OP should do more hacking without fear and less spreading FUD.
I also sincerely doubt that Rust code bases will look the same in ten years. It supports functional and OO paradigms and it's attracting very different classes of programmers. Recently someone wrote a post about difficulties with some OO concepts in Rust, and a top reply said that they never encountered such issues because they program in a functional way.
Go is an exception here, but as soon as they extend the language in a significant way (e.g. templates) differences will start to appear.
C++ doesn't have an idiomatic style because it's used in very different ways by different people. It's impossible to have a fixed style and address the mass market.