Another half a century - Nel mezzo del cammin: Stats

Why is it such an obsession to plan the rest of my life? Is it a peculiar symptom of the mid-life crisis? Does medicine know such cases?
My hypothetical age at death is 98. I calculated it with an online calculator, and I strongly believe it. 50 years of life is 600 months. Till now, I have lived 586 months. Some 30% of my life was spent in my present relationship. My husband elaborated an estimation speaking of some 950 sexual intercourses, but there is a large margin of doubt in this. 
98 years, it gives 1 176 months of life, of which I already consumed 586 months. The remaining is 590 months. In strict mathematical terms, I'm not in the exact mezzo del cammin yet, but I arrive there soon.
In fifty years from now, how many things will still be? Will there still be a European Union? And a France? And a Holland? Or the reality will differ as profoundly from my expectation as my current life differs from my childhood in the destitute communist country, some 520 or 530 months ago? 
There was a time George Steiner seemed similarly obsessed with the potential of the future tense, with our capacity of speaking of the sun raising over our graves. What about the sun raising over my grave? When I feel the death coming, there is one thing I must do. Pay for this website to be maintained online for yet another 10 years. By that time, I believe, people might enjoy the retro flavour of my photos and travel narrations. Perhaps they will taste bitter-sweet as a nostalgic testimony of a Belle Epoque.