That's a misconception. The Maya (not Mayan, that's the language) long count for December 20, 2012 was 12.19.19.17.19. December 21, 2012 was 13.0.0.0.0. Today is 13.0.11.7.4. It continues the same way indefinitely, it's just the number of days since some arbitrary date (August 11, 3114 BCE if you're curious) in base 20, with the second to last digit in base 18, which seems odd at first but it rather cleverly makes it so the third digit can stand in as a rough approximation of years, and the second is approximately a generation. Now October 13, 4772 could be seen as an endpoint but there's nothing that says it can't be extended with one more digit to 1.0.0.0.0.0, and then you're good for another 150,000 years or so.

Now there was a creation myth that said 0.0.0.0.0 was the previous world's 13.0.0.0.0, but there was no recorded belief that this was any sort of recurring cycle, in fact plenty of Maya texts predicted astronomical events millennia past 2012. The idea that it was recurring was probably borrowed from the similar Greek construct of ekpyrosis, which doesn't specify any sort of time frame.