We still don't understand much of the inner workings of our own body. It's a bit like the divide between quantum physics and the macroscopic world. We have successfully observed and modeled individual processes as they happen at a cellular level, and we can draw some statistical conclusions at the whole body level, but much of the area in-between is basically unknown.
One just needs to look at nutrition or the farce that is "nutrition science". We only barely understand what we are supposed to eat to maximize our health, and that's such a basic and fundamental concept that I feel anything like "brute force treatments computationally to fix this gap." would require multiple generational leaps in our understanding. In other words, I feel like you are extrapolating to space flight when we have just recently invented the catapult.
Hell, we are only starting to suspect that the gut biome affects our consciousness. How crazy is that? And yet it is a very sobering indicator of how little we know. The human body is an incredibly complicated system with so many feedback loops that I'd put it in the same class as solving the halting problem or establishing a grand unified theory of physics.
We have modern robotics and tools like laser knives, but we still have to poke needles into a patient's brain to determine where to cut out tumors. I don't mean to disparage the doubtlessly talented surgeons of today, but to me this seems barely above medieval techniques. Our tools have improved 100 fold, our understanding just barely.
I think at best the prediction we can make is that "we believe eventually all diseases should be treatable". But to say that in the next 50 years we can become functionally immortal (treat all diseases), is a very long stretch IMO.