Let's get the hard news out of the way: on July 20, the legacy shop page will no longer be available. This page will instead be redirected to the move-to-vault tool. This move is necessary because the page cannot be maintained any longer.
We will not automatically move items from legacy shops to vault yet, but this is something we've discussed for the future. We won't do this without giving y'all plenty of heads up!
We plan on making it so you can move things from account search and complete quests with legacy shop items. These features will be available on July 24.
I'm not gonna pretend to know what I'm talking about, but I'm genuinely curious: for users who haven't logged in or who have just been dragging their feet, wouldn't it be possible for Subeta to just move all their items into the vault for them and then get rid of their shops?
IIRC it's the page that allows you to convert your legacy shop (the type of shop before the massive shop update a few years ago) into the current version.