I don't know what happens, I don't really think the Heaven/Hell thing happens, but subjectively speaking there can't be nothing. Right at this moment you are conscious, therefore you are not unconscious. Can you describe what it's like to be unconscious? No, because if you are unconscious you fail to perceive, and a description is a representation of a perception. You can't be conscious of being unconscious, which is kind of a self proving statement. In the same way, an area of space cannot be dark and light at the same time, because darkness is the absence of light. It can be less light, but there still exists light, and not darkness. There cannot be nothing after death, because you would need a method to perceive that nothing. That's too easy an answer. There has to be something after death, but it isn't nothing. If there were some nothing for you, there would eventually have to be something, and because you can't perceive that nothing, then time would pass instantaneously, because you would not be conscious of the time passing. From your own perspective, life is never ending. It seems like life ends for other people, but that's just because we don't perceive what they do. So, perhaps, you could die and then simply fail to perceive time moving backward and live your life over again for all of eternity. That's a more sensible argument than nothing at all happening.
Think about what happens when you sleep, (hopefully, every night). You are removed from the everyday considerations, demands, and care for your physical body. This human vessel requires food and drink, protection/ repair from injury, and rest. It is a marvelous construction, able to repair itself, if the damage is not too great.
However, when you sleep, perchance to dream, then your mind is able to explore.
Free from mortal constraints, then you witness the ability to go from place to place in the blink of the eye, engage with curious creatures that your mind has created, or breather while under water, or even fly.
Perhaps this is what it is to be eternal, without our mortal coil?
What if, in the unending charge of eternity, this visit to this tiny blue marble, on the end of a finger of the Milky Way galaxy, is a vacation of sorts, for 80 or so years?
What is 80 years out of forever?
How many galaxies are there?
Maybe we get to choose, before we visit again. That would be pretty cool. If we are truly eternal, then it must be boring to always be the rich guy, the powerful woman, the super intelligent, for a drop in the ocean of time.
Some bored folks (after who knows how many of these vacations to being alive) might decide to come back and mess things up. Evil.
Or, a bug that splats in a windshield on your car.
I just think that this tiny box is not all there is.
I believe the "groups" that formed our body move on to another environment or being. Our minds and conscious won't be there for any longer - but part of us will be leaving as it will thrive for survival whether it is in an environment or a new being. If lucky enough, one day one of these will become another mind/conscious. But we ourselves (our conscious) I believe go nowhere.
When we die, the dust returns to the earth as it was and the spirit returns to God who gave it. Ecclesiastes 12:7. Now what happens to us once we return to God...idk.