WASI in their first attempt has been a success (what now is called wasip1). wasip2, p3, are tied into the component model.

I'd say that wasip1 has been successful, but not any future version. You can check which version is the most popular just by looking at the Rust WASI crate versions and how much downloads each one has:

wasip1:

  https://crates.io/crates/wasi/0.11.1+wasi-snapshot-preview1
  https://crates.io/crates/wasi/0.10.2+wasi-snapshot-preview1
  https://crates.io/crates/wasi/0.10.0+wasi-snapshot-preview1
  https://crates.io/crates/wasi/0.9.0+wasi-snapshot-preview1

wasip2, p3:

  https://crates.io/crates/wasi/0.14.7+wasi-0.2.4  
  https://crates.io/crates/wasi/0.13.3+wasi-0.2.2
  https://crates.io/crates/wasi/0.12.1+wasi-0.2.0