That's a good question, and it's certainly not one I'd want to bet on as Apple.
When they managed to kill off Flash and Java applets, they were getting rid of the two awkward technologies that almost everyone in web development disliked. There were useful replacements coming down the line with HTML5, ES6, and so on. It still took several years for the plugins to die out completely, during which time the browsing experience on Apple devices was noticeably inferior to everyone else's. Arguably it was only Chrome pulling support that finally put an end to the matter.
Today, Apple's reputation isn't what it used to be, with its normally loyal and enthusiastic fan base increasingly questioning the price of new devices, web developers increasingly questioning the lack of support for modern technologies in mobile Safari, native developers wary of Apple's policies around the App Store and how much of the money it's taking for its cut, and the walled garden ecosystem looking increasingly isolated in a world full of connected devices and data sharing. It's hard to see any of these trends changing in Apple's favour any time soon.
Right now, WASM is in its infancy, but if you stop and look at what is being attempted, it is arguably the most important new technology in web development. It's already reasonably well supported across almost every browser that matters, but not yet widely used. But give it a little time to establish it as a target for better languages than JS and to develop supporting tools and libraries, and it's not hard to imagine that in a decade's time we'll all be wondering what we were thinking using JS for so long.