Except that Jetbrains probably makes most of its revenue from enterprise, and Rust has yet to see big enough adoption there (although there is some AFAIK). I'm not sure it's worth the investment yet.

On the other hand this is a chicken and egg problem. A powerful IDE like the ones Jetbrains builds would increase Rust adoption a lot, and eventually Jetbrains would completely dominate that market.

I doubt they'll be inclined in less than 2-3 years.

Still, someone can create a plugin (afaik, there was one but abandoned)