Unless they expressly commit to deleting it, or you were paying per GB for storage, consider it saved forever.
Back in the day I thought "who better to retain a mailing list" but turns out I'd have been best off with a Google Sheet. Now I have to scrounge around in backups to see if I downloaded it anywhere... maybe I should start a support ticket here of my own!
A lot of companies have a habit of keeping data but not migrating dead customers to newer schemas and systems.