Only really two possibilities, an afterlife or oblivion. As a Roman Catholic the afterlife I'd ascribe to is Heaven or Hell, depending on the particular person. Otherwise, it's eternal oblivion, which is also logical. Oblivion is not like sleep, it's the complete absence of being. When you wake from sleep (even dreamless) there is a definite sense of the passage of time, that's not the case with oblivion, it's timeless. The best way to describe it would be to try to comprehend earth before you, that's what it will be like when you're gone, you'll perceive nothing because you will be nothing. I was put under for surgery once and I believe it's very similar, you loose all sense of existence and just fade into the ether. You end when your consciousness ends.
