I'm hoping we see a clearer separation of UI development and JavaScript Backend development. Currently the two are uncomfortably and unhelpfully conflated, which is how you get UI devs being asked to write complex business logic; or backend devs being asked to fix a stylesheet.
While it's entirely possible for one person to do both, it's much more common for people to focus on one or the other.
Assuming WASM has the success it seems headed towards, I think this may happen pretty naturally. Many devs writing JavaScript are only doing so because they had to; and will very quickly move back out to more-suitable backend languages that compile to WASM (technically they could do it now with JS transpilation but it doesn't have the performance gains of WASM).
But speculation is always a bit pointless ;)