I really like this syntax. I wonder if it has ever been proposed for Rust? It should be compatible with the existing semantics and could be phased in and then made mandatory in a new "edition".
There is already a “let” to show you that a variable is being created, adding more verbosity to a feature that, in some sense, is about removing verbosity kinda misses the point, in my opinion.
That said, never say never, but if I was a betting kind of person, I’d bet against it ever being accepted.