There is already RSLint and SWC as JavaScript tools written in Rust and I would expect such tools to take over, with a good choice of it happening before Rome is ready.
Of course, perf is only one reason to use a tool, I expect javascript based tooling to stick around for much longer because developers are used to them now. And, of course, if all you know is frontend, everything starts to look like a javascript job.
But rust also has other features that can help prevent bugs regarding concurrency and more. So rust is a feature in my book and not just an implementation detail.
At this point in time, improvement comes from "anything faster than node". Hell, you might even manage to get a performance benefit out of PHP with the way things are right now.