Are you postulating a "cure" which extends one's life for centuries or through infinity? Given the limited resources here on Earth, that would either be a complete and unmitigated disaster as the world filled up, or it would be the strongest impetus for space exploration imaginable. If people kept making babies at the same rate as before (and somebody apparently did, since Clark has seven generations of descendants), there wouldn't be much room for new people, much less food and shelter for all of them.
Aside from that practical consideration, this is a very touching story. I like the way you turned the life expectancy difference around for both of them, not that I'm glad to read how Clark died, but it's interesting to see that from the opposite perspective for once. And Lois's slightly bitter musings feel natural, despite the prominent position she obviously holds in both her family and society at large. I wonder how Clark felt, knowing that she'd outlive him? Was he happy for her, sad for himself, apprehensive that she might (or might not) find comfort with some other man? Or did she assure him that, after being married to Clark Kent, no other man could possibly be good enough for her?
Being in Lois's situation would, indeed, be brutal. It's good that you gave her such a positive legacy to help her remember Clark.
