Here's my best prediction for how it's could happen: when the all human immune systems are able to learn from each other, we'll be most of the way there. The immune system is at the center of most human diseases. Cancer? It's the best solution. Infection? Best solution. Autoimmune disease?Fixing the immune system would be the best solution to autoimmune disease. Right now, if you want your body to be immune to something, you're immune system has to learn that particular immunity. If we can form an artificial immune system "culture" then it seems like learning could be much, much faster.
It is. That's why immunotherapies have gone from a fringe area to something super hot attracting tons of funding.
But first, we need to understand the cell. For this we believe we need not only statistical learning, but also formal methods. See e.g. a slightly dated but brilliant paper from Luca Cardelli:
I'm struggling to see how that can be done without in vivo genetic engineering (to ensure immune compatibility), constant blood surveillance of the population (to detect pathogens), chemical infusions deployed en masse like a firmware update, and giant cube-shaped space ships.
We'd have to develop an external assay that can ensure immune compatibility. If we're lucky, we find a finite set of molecules that lead to immune incompatibilities from person to person and make an assay that focuses on those molecules.
Constant blood surveillance is already a fact--that is, perhaps we don't need more blood. Instead, we just do the immune sequencing on the stream that's already available. Spread out over the whole population, that's a lot of information. Firmware updates, if necessary, could be handled on an as-needed basis, or more generally like flu vaccines.
I'm not sure how the giant cube-shaped space ships will be handled--that's definitely a hurdle to consider.
How about using commensal bacteria to design an "external immune system" which can respond to any pathogen we program it too. Bacteria coat basically all cavities in your body and could scan incoming threats and respond to them before the human immune system is every involved.
I think we'll create superior bodies for humans that disease never had a chance to adapt to much faster than we'll be able to figure out how to make immune systems communicate without also promoting adaptation from surrounding diseases.
Fixing the existing body is nice, but you're forever limited by what nature intended, and what it intended is just not very good.
