Cardano ecosystem used to use Rust a lot. Currently moving to Haskell. Few other big ecosystems using Rust too.

Imo future is more expressive rust-like languages.

I thought they'd been using Haskellfor years, and the rust development was relatively recent.

Yeah Cardano has been Haskell for years and some Rust for a secondary implementation of the node (Jormungandr)

Polkadot is Rust and WASM based.