Not sure if it will ever satisfy the desire to lenghten human lifespan though. Just as a thought experiment imagine that we have this tech. You have your perfect replica. It responds exactly like you would and no one else, not even you can tell its responses apart from yours. Once you have that, and attained “immortality” as such, do you mind if someone shoots you in the head? The real you i mean. After all you are immortal. Your behaviouraly emulated clone will keep doing what you do, loving your wife, taking care of your kids, supporting the causes you support etc.
For me the answer is that I would absolutely not let my real body killed just because i have my behavioural clone. Which to me implies that at least for me it is not a true continuation of my life. More like having a living will, or a son who is way too similar to me, but still not me.
Basically I would not reach 1000 years. This thing created in my image would.