This is like asking a blind person to describe a painting. There will be events, technologies, and discoveries that we can't foresee. Imagine trying to describe the Internet to someone living in the pre-Columbian Americas. We could probably, with enough teaching and time, get them understand what it is but the context and experience of the thing couldn't be shared. Now imagine those same pre-Columbians trying to dream up the Internet on their own without any external help.

The nature of human existence will be fundementally different than it is now but human nature will not be much different.