I will tell you exactly what happens.
Whatever you want to happen.
If you believe Heaven exists, and you will go to Heaven, you will... if you believe in God, then he exists... if you don't believe in God, then he doesn't exist. If you believe you are dead and gone, (after death,) and there is no other world or life out there, then that is what will happen to you.
If I believe in God, then he DOES exist, if you don't believe in God then he DOESN'T exist. It's all subjective and no-one has any right to tell anyone else that their beliefs are wrong.
Everyone is entitled to their own opinion and view, and no-one can tell anyone they are wrong, because no-one actually knows what happens.
I always find when this subject comes up, people who don't believe in life after death (or Heaven,) rush to mock and deride people who DO believe it. Yet I don't see anyone who DOES believe, taking the piss out of the naysayers and disbelievers.
Speaks volumes really about the disbelievers. They are, more often than not, rude and ignorant about other people views and beliefs, and don't give a shit about their feelings, or how their comments hurt.
If you don't believe, then don't. But bore off with your rude comments, and mocking those who do!
Re Stephen Hawking saying 'you just die and that's it,' I had a lot of respect for this brilliant man, but he had no more of a clue what happened after death than I do, (or anyone else on this forum.)
@ginmakesitallok
I think it's pretty arrogant to believe that anything special happens just because we're human.
What a laughable and ludicrous thing to say. 
Everyone is entitled to their own views, but they are NOT entitled to take the piss out of the views (and beliefs) of others.