alt Hacker NewsTypescript was Microsoft and Swift was Apple, so those follow the same pattern of Go and Rust.
10 years is enough time. The industry was absolutely using Perl (1987) in 1997 and I was using Python (1991) professionally by 2003.
I mentioned Zig already; Julia also feels like it fizzled in a similar way, by getting attention without commensurate adoption.
But I will concede that you're right about Lean. It feels important that it's solving tomorrow's problem (i.e. today's) rather than yesterday's problem.
Well there was perl 0 from I'm-not-sure-when before perl 1. Similarly Python started development in 1989. Mojo seems to be the most prominent of the new languages, but I suspect there are plenty of things out there waiting to catch on. I suspect there will be a generation of people who will have seen the advantages of Rust who will go on to attempt to write a language that keeps those advantages but doesn't invoke the trauma of Rust.
Things do go a little slower these days however. It was 5 years and one month between the release of the Vic-20 and the Amiga. How different is your computer to the one you had 5 years ago?