As a moderate rationalist, I believe that what happens to a human being when it dies is effectively the same that happened to it before it was born: Nothing. It does not exist, hence it does not perceive anything nor is it perceived by anyone nor does it affect anything within the system of the universe nor does it affect any other system that might exist. It's just not there or somewhere else. It does not exist. Circle of self-perception/self-imagination broken. The end.
Like Christianity, I believe that the human being has an eternal soul. Only my perspective is different: I think Christianity has the wrong concept of Heaven and God's will etc.. In my opinion, evolution itself (whether kicked off by God or not) will turn our very universe into Heaven! Not to forget: The human mind is not an outside observer of evolution but an active participator. Like Bill Hicks said: "I think it's time to evolve ideas." Eternal life might come biologically or it might be introduced by human technology. People will stop dying etc., so they will have eternal souls: Their bodies and minds. Unlike the existence Christianity believes in, this very merciful system allows to end the experience by means of death.
Death is a true miracle, everyone who feels that there must be something eternal about their lifes kind of have to agree with me. Problem is that death is currently mandantory, but I think this bug will be removed when evolution has completed its work. Death will stay as an option, but I guess no one would chose that option because who would shut off the camera when there's so much good stuff (and no bad stuff) to be experienced.
"Oh, I think humans need negative experiences every once in a while, otherwise they would not be humans. They would not know bad from good. They would not appreciate happiness." Bullshit. Whoever believes/preaches that suffering has to be an integral part of life needs to get their head examined.
I think that the human being ultimately has the capacity for good merely based on the *perception of beauty*. A smile of bliss and happiness is beautiful. A healthy and happy human is beautiful. It is a beautiful thing to experience to be happy about someone else's happiness. I think that this is ultimately what Love is, and I think it does not have to be beaten into the perceivers. Evolution is still underway. When it's done, Love will be default and the dark times will be but a weird memory.
You are a "cockeyed optimist" if ever I saw one, but you are not that realistic about what your fellow man is capable of. The brain is the most important factor of life. Without the brain there is no life. I do not believe that there is any basis for the belief that there are "souls" floating around. It's very unlikely.
A way to run a brain in software is what we would need for eternal life, and I don't doubt that we will get there. But I doubt that any of us will be around. Unless there are people who will have the brain removed from the dead body and stored. They are probably doing that right now through cryogenics.
We could live forever by uploading the human brain. Then we could make digital copies of ourselves. That's going to happen.
The Stepford Wives by Ira Levin, was a variation on that theme, but it was about making women into life like robots, and I believe there will be life like robots.
Forget about the souls and the beautiful world I think it will be run by the same nefarious group that is presently in charge. I think it will be a way to have people that are virtual salves with a few "favorite sons" in charge. Just like now, and I guess it depends on who you are if it's heaven or hell.
Or they could create a genetic therapy to repair the telomeres so that they are longer or so that they don't shorten at all, you might be able to live forever. They could probably do that if they wanted to, but I don't think they want people to live very long right now. Only if we really find a way to explore space and find inhabitable planets will they need the manpower to make them want us to live longer. I still think that they will always find a way to make men into slaves. That's why they invented religion to begin with. There may eventually be a corporate "live forever through technology" industry, but it will be the most rotten people on the face of the earth that will be living forever.