... and arguably evil, too, though let's set that aside.
My plan requires the truth of a psychological theory of personal identity, a "vehicle externalist" account of memory, and some radical social changes. But it requires no magic or computer technology, and arguably we could actually implement it.
Psychological theory of personal identity. Most philosophers think that personal identity over time is grounded by something psychological . Twenty-year-old you and forty-year-old you are (or will be) the same person because of some psychological linkage over time -- maybe continuity of memory, maybe some other sort of counterfactual-supporting causal connectedness between psychological states over time. Maybe traits, values, plans, and projects come into the picture, too. In practice, people don't have the right kind of psychological connectedness without having biological bodily continuity. But that, perhaps, is merely a contingent fact about us.
Vehicle externalism about memory. What is memory? If a madman thinks he is Napoleon remembering Waterloo, he does not remember Waterloo, even if by chance he happens upon exactly the same memory images as Napoleon himself had later in life. Memory requires, it seems, the right kind of causal connectedness to the original event. But need the relevant causal connectedness be entirely interior to the skull? Vehicle externalists about memory say no, there is nothing sacred about the brain-environment boundary. External objects can hold, or partly hold, our memories, if they are hooked up to us with the right kind of reliable causal chains. Consider Andy Clark's and David Chalmers's delightful short paper on Otto, whose ever-available notebook serves as part of his mind; or consider a science-fiction case in which part one's memory is temporarily transferred onto a computer chip and then later recovered.
Implementation. Could one's temporary memory reservoir be another person? I don't see why not, on a vehicle externalist account. And could the memories -- and the values and projects and whatever else is essential to personal identity -- then be transferred into another human body, for example, over the course of a decade or two into the body of a newborn baby as she grows up? I don't see why not, if we accept at least somewhat liberal versions of all the premises so far, and if we assume the most excellent possible shaping of that child.
By formatting a new child with your memories, your personality, your values, your projects, your loves, your hopes and regrets, you could thus continue into a new body. Presumably, you could continue this process indefinitely, taking a new body every fifty years or so.
As I said, a madman's dream of being Napoleon is no continuation of Napoleon. But the situation would be very different from that. There would be no madness. The memories would have well-preserved causal traces back to the original events; the crucial functional role of memory, to save those traces, would be perserved; everything would be held steadily in place by the person or people implementing this plan on your behalf, as a stable network of correctly functioning cognitive processes. And the result would be not just something on paper or in a memory chip but a consciously experienced memory image, felt by its owner to be a real authentic memory of the original event.
This could, it seems, be done with existing technology, using clever mnemonic and psychological techniques. One would need mnemonists who knew everything possible about you, who observed the same events and shared your same memories, and who were exceptionally skilled at preserving this information and transferring it to the child. The question then would be whether it would be true that the child, when she grew up, would really be you, with your authentic memories, instead of a mad Napoleon. And the answer to that question depends when whether certain theories of personal identity and memory are true. If the right theories are indeed true, then immortality -- or rather, longevity potentially in perpetuity -- would be possible for sufficiently wealthy and powerful people now, if they only chose to implement it.
I have written a story about this: The Mnemonists.