On the issue of the world changing in 2012 I have mixed feelings. This is my interpretation of how things work and is likely how the Mayan's viewed things as well. First it is important to understand that while it is ever changing and chaotic, everything in the known universe runs on cycles, rotations, and repetition at its most basic level. This phenomenon was observed by many ancient cultures around the world and it is no surprise that they formed similar conclusions. The reason for this worldwide astronomical understanding is that the ancient world was so much more connected to the cosmos then we are today, their lives depended on it! Modern cultures are dulled by the instant gratification of information that sprung from technologies like the web in the 1990's, and by television in the 1950's, and by radio in the early 1900's and as far back as the first mass printed material that was widely available. In ancient times, information we may see as trivial today was something magical to them, a treasure that was known only by a select few and in many cases was only available by word of mouth, or kept in sacred places like Stonehenge, the tombs and temples in Egypt, or other ancient fonts of knowledge.
With that said, and all of us in agreement that the universe runs on cycles, rotations, and repetition, the next bit of information we need to discuss is; ancient cultures like the Maya realized they were not indispensable. Unlike modern people the Maya knew, or at least were consciously aware that they were floating around on a rock, in the middle of space, and were helplessly susceptible to an onslaught of cosmic cycles and phenomenon outside of their control. They began to watch….who knows for how long. They began to make associations with these cycles; and cataloged the behaviors of men as well as the Earth and viewable cosmos when they occurred in something called a codex. In fact, their entire culture was built around these associations. So the information in the codex referring to events or dates on the calendar would not be prophecy at all, but perhaps thousands of years of observation and associating various cosmic and earthly cycles/events and mans usual reaction to them.
What the Mayan codex associated with this coming cycle was rapid societal change, upheaval, an awakening of human consciousness, a return to the Earth, and water…. I suppose you can weave doom into that, but this would have been a glorious and profound thing to them, a time of rebirth and growth. The beginning of a new cycle. A resetting of the calendar. And yes, the calendar does in fact go on, there are many references to dates and times beyond 2012.
Do I feel things will begin to change with the coming cycle? Most definitely. Do I feel the Earth will end by a giant planet smashing into us, or a some other Earth ending event? No I do not. Something as epic as the destruction of the Earth and its gravitational orbit would disrupt the entire flow of the cosmic cycles, and possibly even cause damage elsewhere in the galaxy. I just don’t feel it is going to happen that way. If I am wrong and it does occur, I still doubt it will be meant as a judgment or some other form of punishment on humanity. Humans are just not that important on a universal scale. It is our own intelligence, fear and arrogance as a species that puts us in a position of importance in our own minds. When in reality, life on Earth was here a long, long time before we were, and is likely to be here long after we are gone. We are frankly little more than a self-destructive footnote in cosmic history.