From T289337:

Please note that with the recent decision to set up a new shared Vue component library (https://phabricator.wikimedia.org/T288980) under changed technical aspects, we're going to put WVUI in maintenance-only mode and hope to bring the best parts (including existing components) over to this new library.

The instructions in the README/CONTRIBUTING file should be updated to reflect this intention, and instructions for where to go next should be added when that is known.