It took 10 years for WebGL to be widely available, and it is still barely used beyond some niche use cases like 3D models in ecommerce, or Flash's revenge when coupled with WASM.

With WebGPU it will be faster - libraries like ThreeJS will use WebGPU when possible.

ThreeJS doesn't even has a good alternative to having a complete incompatible shading language, other than switching to graphical based shaders.

Do you expect everyone to rewrite 10 years of shaders just for fun?

Yes.