It may stop Rust from getting widespread adoption, but I see no problem with that. C++ isn't "widely used" either by most meanings. Rust may still largely replace C++ even without magically having a less steep learning curve. (Which it, IMHO, actually has anyway.)
As someone who learned C++ first and later Rust, no it isn't. Rust's learning curve is a hell of a lot higher than C++'s.
This reminds me of when Java was trying to compete with C++, you would have all these Java people making claims that HotSpot was going to take over the world and make Java faster than C/C++. Only it never happened outside of a few specific cases because these people were "fanboys" in every sense of the word.
You like Rust, there's nothing wrong with that. You think it's better than C++, that's your belief and I'll defend your right to believe it.
But stop comparing it to C++. Just about every language over the past 20 years has users do the same thing and __C++ IS STILL KING__.
You can push rust without being unfair to C++ (NO WAY is C++ harder to learn than Rust).
Depends on what you mean. Writing good, safe, C++? Quite hard. Debatably harder than Rust, but it's debatable, not an absolute statement.
The difference is that C and C++ let you write things like doubly linked lists in day 1 of learning them, whereas Rust won't. But a good doubly linked list is tricky to get right anyway.
I learned C++ first too, and I think I have a handle on "safe" C++ practices, but it's mostly a nebulous set of conventions that shift in the particulars based on the codebase. OTOH in Rust I'm immensely productive even in random codebases.
Most of the cognitive overhead of Rust exists in C++ too, since you still need to reason about how your data is shared, just that C++ spreads the cost out over the learning curve, whereas in Rust you have to deal with it up front.
I've been programming C++ for 16 years, it's the main language at my day job, and I won't even begin to think I understand templates. But you'll see codebases that use it regularly. Const correctness? rvalue vs lvalue? ODR? SFINAE? RVO? exception safe code? template argument deduction? Then you have C++11, C++14, C++17...
Despite this, I still regularly write code that has memory, string, concurrency and bounds bugs. So does everyone else in the industry, including smarter people with more experience.
It's possible that the parts of Rust I'm not familiar with (e.g. unsafe code, macro system) turn out to be similar sinkholes, but so far, that doesn't seem to be the case.
I had the exact opposite experience, i.e. Rust allows me to not worry about memory safety and allows me to think on a much closer level of abstraction to my problem domain than C++.
Anyone who thinks this is what it means to learn a language is attacking a strawman.
OTOH, many students of programming languages learn by pushing their code (EDIT: ready or not) into production. Oh boy do they learn.
The parent post specific said it wanted a replacement for C++; the amount of time and effort it takes to get code right in C++ is a problem.
Rust also has a long learning curve, and its hard to quickly be productive in.
I don't think there's anything wrong with idly wishing there was some kind of middle ground where you could gradually or partially opt-in to the borrow checker with a nice modern language like rust to get started, and then gradually eliminate your GC parts or whatever.
Many game engines use a high level language with a GC like C# or (shudder) python or blueprint which are baked by C++ for the performance critical parts.
You write application logic in the scripting language, and anything that's too complex you fall back to C++ for.
If rust could somehow self host itself as a high level language like that, it would be superb.