I think all of this end of the world stuff is crazy. However, it may not be too far off. But, only with media and the internet (and its idiots) to blame.
Why? Because I believe that there will not be any scientific means to cause the end of the world, but the sheer panic will be the cause of the end of the world. Well, not the "end", but global chaos will probably ensue.
After all, we had a minor panic with Y2k, but the media didn't hype Y2k nearly this bad. There will be riots, panic, and sheer chaos for a while as the panic from the "believers" spreads, and people do crazy shit they would never do, since they are planning to die.
We've all seen the riot scenes in movies. Take "The Simpsons Movie" for instance, how Springfield went insane with vandalism and riots when they were trapped on the dome, thinking it was the end. I expect to see a widespread version of that, but nothing "earth ending".
Or maybe it will? Maybe we will be the cause of our own end. What do you think?
Personally, I think there will be riots as I said, the day will come, nothing will happen (except overtime for law enforcers), and after a few days (or maybe a week), the mess from the whole ordeal will be cleaned up, the rioters locked up, and the world will go on as if it never happened (except for another lame movie or 2, perhaps).