Anyone who has actually STUDIED the Mayan Calendar and the surrounding culture knows that at the end of the cycle, it merely starts again.
There is some expressed hope in the ancient texts that people alive at the time will use the time as a time of thoughtful introspection, but it is like Gregorian AD 2,000 — interesting but no more than a mark on a line or the turn of a calendar page.
Well, I have had a ton of calendars which ended on December 31 of any given year, and the world hasn't ended yet.
Maybe they should have put "see other rock" or "lather, rinse, repeat" or somesuch on the calendar...