Do you have a link to the source for that? I'm curious to read.
If your description is accurate, Rust[1] is exactly what he wants. I've been learning Rust recently (with a little help from [2]) and it does a ton of static code analysis, is safe by default (no dangling or null pointers, no shared mutable state), uses Hindley-Milner type interface just like Haskell, and generally is what you would expect if Haskell and C++ had a baby.
Rust is pretty much exactly what a lot of people want and need; a high level language with a strong focus on safety and concurrency, while still allowing you to control the lower level details such as memory layout for good performance.
He sort of alluded to it, but there's the usual perceived tooling/ retraining/hiring / performance ceiling issues for shops with > N devs, N somewhere between 5 and 25 (I don't agree with his arguments, just repeating them)
Oh of course, it's far from trivial to switch to a new language. But if you're writing code you'll still be using in 10 years, the maintainability benefits of a safer language like Rust could be pretty huge. Also, Carmack switched from C to C++ not too long ago.
That wasn't for functional programming though. It was instead for the built-in static code analysis the Haskell type system and compiler provides.