Do I think the mayans had a very advanced lunar calender for their time yes, do I think they are predicting a end to the world? No. In fact to them it's actually just the start of a new life cycle be whatever that was to them. As a heavy astrologically influenced society the event of crossing through the center plane of the galaxy I'am sure held a great importance to them as a major event. I don't think however they thought it would be the end of the world, and I don't think it will be for us either.
As far as pole shifts they have happened in the past we have science has proven that. Will it happen again? Very likely.. when? who knows? How much they will shift? Who knows? If a pole shift does happen will it be the end of the world? I highly doubt it.. it could make our lives difficult at first and maybe claim some lives, as climates will likely drastically change and natural disaster's such as floods, storms, tsunami's etc will likely take place over a period of time as the climate changes and settles into its new cycle. Also the possiblity for changes in our magnetic field could allow strong solar flares to cause disruption possibly shorting out electronics, frying transformers etc.. Nothing that will end the world though all things we could rebound from.