But that's what makes it fun, don't you think? And what's more blasphemous is that people insist that it could be anything but the Zombie Apocalypse! :P
It's not gonna happen, who ever made probably didn't have any more room (like what Gonzomon said), got tierd or was killed by the Conquistadors before they can finish creating the calender.
If the end of the world was supposed to happen, then everyone should already know how it's supposed to end. Otherwise, let's just forget it's going to happen and conclude that the Mayan calendar is just going to repeat or something like that.