If the crack can erase you from time itself, would it erase Jack and his immortality?

it would erase everyone from existence wouldnt it?

Oh come on - this whole thread was set up just to get filthy comments out of us.

It won't just kill you, you'll never have been born. So yes, it can eliminate Jack completely.

Maybe it'd make him spend a year fighting extremely tedious 'adult' monsters, a year doing genre cliches and then a quick week of reasonably decent event television?

What we have here is a paradox. Jack enters the time crack and is killed as a result of going in there, but wait... he's not killed because he didn't exist, because we went into the crack, but he did exist before he went into the crack. I think it's a paradox that even Jack can beat. I think what would happen would be he would forget everything about himself like some sort of "human vegetable" until he'd had time to "heal" himself.