Not the op, but there's more to frontend development than JS. You need to account for the API of browsers, the DOM, CSS and the myraid of frameworks and libraries built for the specific UI requirements of frontend development (e.g. React). So even if your favorite language of choice becomes compilable to WebAssembly, you'll still be learning an entirely different way of development that will be completely unfamiliar regardless.

The only thing I see languages compiled to WebAssembly taking over is development of highly resource intensive applications, algorithms or libraries. Or if there's a quantum leap with some specific language + framework that eliminates a lot of work with current frontend development. Otherwise, there will be too much fragmentation and you'll see the regression to the mean effect as has been the case with predecessors such as CoffeeScript, Elm, PureScript, ReasonML, and every other compile-to-JS language du jour.

A paradigm shift could happen and what's cool is that it could be entirely something new. This reminds me of the early days of the WWW when the first programming paradigm was Perl/CGI, then Cold Fusion, then Legacy ASP, and then ActiveX, and so on.

The possibility of some company creating, from scratch, a new web development paradigm, given everything we know today, is exciting.

Sure, and based on historical precedent, that's almost guaranteed to happen. But I doubt it will be whatever-my-favorite-backend-language-of-choice-is and more likely some-domain-specific-language-and-new-framework. In other words, we'll all be relearning everything again 5 years from now.

Java applets were supposed to provide that in the 90s. Netscape was going to actually embed Java in the browser as an alternative to JavaScript, but there wasn't enough time, so they just shipped with JS, and Java was provided via a plugin.

As a fellow backend developer I certainly hope so. I think web assembly gets us very close. Only two things I missed were direct canvas access from C++ without going through a JS shim and access to some kind of blob storage api in the browser.