Imagining the Future

At Alan's yesterday what stands out for me is a discussion about why someone wouldn't want to live forever.
Economic issues seemed to be the main concern. Some people seem worried that they would not be able to support themselves as they got older and older. Others were concerned about health issues.
Patty's dream is a symptom of those fears, I think.
I wonder, why imagine that sort of eternity at all? What would lead one to suppose that the "reality" they are experiencing is all there is to experience? Why envision the "same old"? Why not new improved and infinitely improvable? Think Different.