Marriott uses a non-published 'last-chance' standard to help MR members retain some status when their stay activity falls off a cliff (like mine did in 2003). Marriott will average your stay activity over the three previous calendar years and use that number to determine your holdover status. In a lot of cases, that results in a more-or-less soft landing. In my case, I had a horrendously large number of nights in 2002, so I retained some (otherwise unearned) status for three years even though I wasn't on the road any longer.

The MR elite desk clued me in to this when I called up in 2004 to thank them for keeping non-stayer me in the elite family.