The Mayan calendar, or, precisely, calendars, because there is a long count calendar and a short count calendar, is circular, rather than linear like ours. And the two intersect as interlocking gears. They, and Mayan time, keep turning. There is no "cosmic clock finally winding down to zero days." Instead, the "wheels" turn, the cogs of their gears re-engage, and a new cycle starts. I believe the illustration you used has been cropped to remove the long count calendar. You can see both, and how they are enmeshed, here.
http://www.viewzone.com/endtime.html
