If you're presently younger than early middle age, and not headed into a life of abject poverty, I'd say it's a fairly safe bet that you won't die from Alzheimer's or Parkinson's. Cancer ("malignant neoplasms" to the actuaries) will likely be a chronic annoyance to your health and bank balance - but not fatal. Heart disease and diabetes will be eyed much as tuberculosis is today; killers of the past, now tamed. In short, the causes of the larger numbers in mortality tables will fall to the advance of medicine; some within a decade, others lingering longer, but there seems little doubt that scientists will nail them all within a generation of breakneck research in medicine and biotechnology.
What, then, will be the causes of age-related death 30 years from now? The body is an exceedingly complex machine; blocking off one failure mode, or preventing a single mode of death that results from a class of accumulated damage will leave many other possibilities. Behind the neurodegenerative diseases we know lie a hundred, a thousand ever more subtle and devilish ways in which age-related cellular damage can kill us. You can plug as many holes as you like, but eventually you're going to run out of fingers.
We can plausibly look forward to sidestepping this problem of ongoing damage by replacing an old heart with a young, tissue engineered heart lacking age-related damage. We are within a decade or two of being able to do the same for any other organ or system within the body ... but not the brain.
This prospect of unending discovery of new failure modes - and the long development of a cure, all too late to save those unlucky enough to be at the head of the queue - is one of the reasons that an engineering approach to fixing age-related disease is so attractive. Rather than play catch-up and research with ever more complex consequences of age-related cellular damage, let's identify, repair and prevent that damage. Strike at the root, in other words, by taking the path of greater effectiveness and least complexity. If we can do that, there would be no need to determine and decipher the fatal neurodegenerative conditions that follow Alzheimer's - no-one will ever accumulate the damage required to suffer from these presently unknown killers.
This seems to me to be a far better path forward, that the present dominant paradigm of medical research, and is why I strongly support greater funding for research programs and proposals that take this approach.