People should stop trying to guess. Throughout history, these predictions have been made based on anything from a feeling to ancient writings to astrological signs to supposed visions or dreams... and they've all been wrong. What's more, such predictions will continue to be wrong. No one will ever get it right.
No one knows the year, day or hour. We're not supposed to. The important thing is not when humanity will end, but rather what you do with your life until then. Treat people right. Have fun. Enjoy life, but always live for others before yourself. Your own life is far more likely to end before humanity as a whole ceases to exist on earth, so rather then speculating on the end of days, focus on the short term.