If that was shipping today, it would be another 7-10 years for browsers to catch up. At wasm's current rate, it won't be available for another few years. The ability to make decent garbage collectors also looks to be very far out.

If you are writing JS today with even a couple years of experience, it's guaranteed to be used for everything until you retire (well, if retiring from a company after putting in your 20 was still a thing).