For a smallish subset of use cases, maybe. But replacing the DOM with a canvas-based UI for general use would be reinventing many of the problems of Flash.
Gamedev is a separate topic. As for designers, they are on the opposite side from users in the tug-of-war of control over content rendering. I don't believe they should get 100% of their way.
WebGL bindings are on the same footing as DOM bindings- they're not an alternative in this sense, because insofar as we have one we already have the other.
What I'm saying is, the feature/mechanism that lets WebAssembly call WebGL or WebGPU is exactly the same one that lets it call DOM APIs. The same implementation work supports both.