This is actually tough to answer because of rapid gains in bio and nanotechnology. In the next few decades, it’s looking no unreasonable to see our understanding of genetics and cellular activity become so thorough that we can design nanobots to repair defects or even “improve” and alter the genetic code. If we can regrow and implant any failing organ, halt the growth of cancer cells, or target viruses more effectively than our natural immune systems, what’s to kill us besides trauma?
This isn’t to say this will happen for sure, but like I said it seems reasonable. Given these developments, I’ve read people could theoretically live for hundreds of years. Sounds crazy, but I work in biotech and have seen rapid advances in 10 years.
I’d guess in the next few decades, certainly within this century, the wealthy will find the means to significantly extend their lives. Eventually, this technology should be more affordable, but it opens a whole host of ethical issues about life: if someone is poor do they get a new heart? Do they get the benefit of the technology that keeps their muscles in the same shape as in their 20s? Or does extended life become the domain of the “haves”, not the “have nots”? Also, would it be responsible to have more children? Imagine playing with your great-great-great-great-grandchildren.
Anyways, sans said advances, I think I’ll live into my early 80s. I eat well, exercise all the time, but I’m 6’4”. You don’t see a lot of tall elderly people, and I’ve heard their hearts eventually have trouble keeping up. I could be mistaken about that, but I’m guessing I’ll be 82 or so.
How long would I like to have? Hundreds, maybe thousands of years, provided I’m in good health and can think.