There's a bit of a push to get everything that isn't rendering out of the render thread, and if you're going to do a bunch of logic in a web worker I guess it isn't a big jump to do it in Go/Rust/whatever.

I agree with your intuition, though -- I don't think it'll become too widespread. Projects will start in all-js in the front-end, and no language will provide sufficient benefit to motivate rewriting half of the client.

I'm less sure about back-end development trends but I think "less standardised than the front-end" is a gimme. Maybe Node/Express or similar will pick up, but I feel like they've been waning the last few years. Go servers seem trendier.

I’m optimistic about Elm or something like Elm that represents a minimal core of today’s emerging best practices (virtual DOM, static types, functional core & imperative shell) while cutting off the fat (mutability, type coercion) and providing valuable affordances and guarantees (educational compiler messages, no runtime exceptions.)

Why?