It should be possible to create a lower-level IDL that starts with byte streams and makes no assumptions about performance requirements and the transport layer.

It should be possible to create a lower-level IDL that starts with byte streams and makes no assumptions about performance requirements and the transport layer. Any language would be able to decode byte streams according to provided schema into intermediate formats (same semantics, different implementations) with a library, and then decode that significantly easier to understand data into application-specific formats. Rust's Serde is almost there, but uses dynamic structure instead of using a schema that allows custom types.