Indeed, a legacy version of Volar is necessary so that those maintaining both Vue 2 and Vue 3 projects don't have to worry about Volar version updates.

We are in the same boat. We have a couple of big legacy vue 2 apps, it would be great to have a "vue legacy" extension

I've always been keen to take on the task of updating a large Vue 2 project migration to Vue 3. I would be up for it if anyone's open to hiring. I've done a fair bit of dabbling in it in the past. From my experience, the issue is mainly the other Vue libraries, which must be converted simultaneously. The best I've got on my CV is a 500-component strong rebrand, so a large migration would be right up my street. But i agree a legacy version would be handy just to avoid breaking changes in the future if your focus is off Vue2. Just like the Chrome extension legacy version.

Strongly agree! I also have multiple projects using both Vue 2 and 3. Extensions like "Vue Legacy (Official)" could clearly state from the start that they are a fork of the "Vue(official) 3.0" package, providing only essential bug fixes and maintained until a specific end date (e.g., XX year XX month).

Ideally, this could be handled automatically—such as reading the Vue version from package.json to switch extension features accordingly. Even manual switching would be acceptable; users could be advised in the extension’s description to disable the extension for specific projects via the "Disable (Workspace)" option in the extensions panel. This is far more convenient than constantly upgrading or downgrading manually.

This approach allows new Vue 3 projects to take advantage of the latest extension features, while still supporting older Vue 2 projects seamlessly.

useful idea! vue2.7 existed using there, hope it!

For what it's worth, I upgraded our 600+ component code base in a few months (webpack → Vite, Vuetify, and Vue) a couple of years ago. That was in parallel with continued feature work. It's not a small project, but the component changes are much less than I had expected. The Vue 3 upgrade guide and Vuetify upgrade guide made things pretty clear. The vue 3 linter config (vue3-strongly-recommended) and Vuetify linter config (eslint-plugin-vuetify) took care of most of the little changes automatically (always double-check it) and made the rest easy to see. That's just to say that it's not only worth prioritizing, but might not be the blocker that it seems from the start.