They didn't suggest the web is doomed, just that more aspects of it are opaque. I don't think they're talking about every day users of the web either, but rather nascent developers.
The early web was a great equalizer. Anybody could study a little html, download an ftp manager, jump through a few procedural hoops and have a web page. After some studying and trial and error they could even build an interactive site.[1]
It's easy to miss all the potential of wasm when that's what you remember of the web. To me the amazing thing is that browsers will still work with the methods described above[2] but we're on the cusp of being able to do almost everything a full application environment can do.
That said, even though there will be plenty of OSS wasm tech, it'll still be more opaque to those of us who don't do compiled languages. It'll be a lot tougher to just fork the code and do something more creative with it.
[1] PHP used to stand for "Personal Home Page" and, as one of its founders put it, was created so that "any idtiot" could make an interactive site.
[2] https://t.mkws.sh/58bytes/