I think the only way the web could remain mostly-JS apps, is if the benefits of writing mostly-JS apps would outweigh the benefits of writing, well, not-mostly-JS apps.

And I'm not sure if that's gonna be true.

For example, I'm sitting here, arguing for an open and readable web, and yet I can't wait for a rust-to-asm.js workflow to get stable enough so that I can move the perf-critical parts of my app to rust (you know, the part that could be learned from and hacked on by another developer).