WebXR feels like a solid building-block to me. Adoption will be (and has been) shaky, but with Apple being forced to adopt third-party browser engines it's revival seems likely.

WASM is neat but extremely finnecky at the moment. I've seen cool stuff done with it, but I'm not convinced it's funny production ready yet.

WebGPU is sorta in the same boat as WASM, if a little more realistic of a bet. People will want hardware-accelerated browser experiences soon, and WebGPU will probably do most of the lifting there.

The content pipelines aren't there, or visual fidelity.