"It's a C-like OCaml" was how Rust was originally described to me, when I first heard of it.
I am not really even criticizing Rust. Let it be what it is. Python isn't C++ either. All I'm saying is that if the goal is to increase the number of people using memory safe languages, adding a borrow checker to C++ would serve that goal.
(Also, I would really like to have a language with both a borrower checker and actual C++ templates.)
(And yes, I fully support making C++ safer too; the GSL is as close as we're going to get, probably.)
How about a language that embraces Turing-complete template metaprogramming as a thing to design in on purpose rather than something discovered after the fact to be more useful than anticipated. Have the utility without the ugly.
(And the reason it's taking such a while is that we are actually doing that...)