Keep features on workflow board when assigned user has been removed

What is the challenge?

Working from a workflow board (with multiple workspaces) when an assigned user has left the company.

What is the impact?

A feature disappearing from view makes it harder to find (to move through last deployment statuses, or to re-assign) since one has to go find it on the features board.

Describe your idea

Keep features visible on workflow boards even when the assigned user has been removed from having access.

(For those who use "group by: user", show it under a section called "Unknown User" if using the user's name from the card isn't as easy as it sounds.)