I'm always reminded of Gary Bernhardt's "the birth and death of javascript" when wasm gets discussed. While it's a bit tongue-in-cheek, I think it really drives home that it's really just another layer of abstraction that may or may not be useful for a given problem, and might not be the silver bullet that anyone is looking for. I recon that whether or not wasm will take over everything will mostly be about trade offs between it and the other solutions.