I've seen some great development environments where all of development/debugging is unbundled ESM directly in the browser. It's going to take a lot of momentum shift to swing the "bundler pendulum" back away from "always" to "as needed" (or even, shockingly, "never"), but I think it is going to happen. HTTP/2+ really does make "never" a bigger possibility than ever before, especially in cases like MPAs (and SSR SPAs that don't mind slower hydration outside certain fast paths).
Also, even some cases with bundlers, some of the modern bundlers (esbuild and swc) are still directly bundling to ESM now as the target. Lazy-loading boundaries and common/shared-code boundaries are just ESM imports and there's no "runtime emulation" there, just native browser loading at that point. They are just taking "small" ESM modules and making bigger ones.
Also, even some cases with bundlers, some of the modern bundlers (esbuild and swc) are still directly bundling to ESM now as the target. Lazy-loading boundaries and common/shared-code boundaries are just ESM imports and there's no "runtime emulation" there, just native browser loading at that point. They are just taking "small" ESM modules and making bigger ones.