The scientific breakthrough you most hope to see in your lifetime

And yes, this question assumes that nobody comes up with a way for us to live forever (although you never know). But seriously, there are a ton of scientific projects making exciting progress right this instant — personalized medicine, the search for dark matter, and so on. If you could only pick one breakthrough that you’d get to see before you croaked, what’d it be?

I’m going to go "big but realistic" here, mostly because I’m obsessed with this specific branch of research. But regenerative medicine has made huge, huge strides in a very brief period of time — and I think it’s only the beginning. So I’m hoping to see regenerative medicine break into the mainstream in an enormous way, with lab-grown cells or organs available "on-demand" and tailored for specific patients. Need a new kidney? Done. Desperate for a fresh heart? Replacement is ready. Obviously, this would have absolutely enormous implications (fodder for another forum thread) of which I can hardly even start to wrap my head around.