WGSL (The WebGPU Shader Language) is already a Web standard, already has structs, and already suffers from the lack of structs in JavaScript, as JavaScript needs to pass data to the GPU in buffers.
TypeScript is a fad.
Edit: I don't mean to crap on TypeScript, but I remember when everyone assumed CoffeeScript was the future. Things come and go, but we can't break the Web.