6,000 JIRA tickets: Assuming you do two weekly sprints, you calculate which sprint would fall into the two weeks after you retire, and that’s where they go.
Seriously, that’s a task for your manager’s manager’s manager. But I thinthink it’s possible in JIRA to close 6,000 tickets as “Won’t do”. Better yet: “Need more information”. Even better: Call a meeting for prioritisation. Invite someone two levels higher up, just for the first ten minutes. Print out all the JIRA and bring them in boxes. Just to demonstrate the absurdity of this.