We always forget science and new ideas are not locked in separate vacuums. For example: the invention of concrete, then the invention of the elevator, then the invention of reinforced concrete, then the invention of sky scrappers... All together took 2000 years...
Now what is 2000 years if we can live to a 1000 years? I don't believe no other scientific discoveries will be made in a 1000 years. Propulsion, cheap energy, new "impossible" materials, etc...
Don't forget: Even if you start the treatment of living up to 1000 years at let say 70, you would gain 30 years of youth for the first time. Then the progress and the numbers of years you'll ad up will be exponential. Just like Moore's law and so many other advances in human technology (besides the pyramids and other multiple ton monuments we have yet to know how to re build but that's for another thread...)
So a "lifetime" to reach another planet or for people to get on other places, low cost space building cities, etc, will take place at the same time people will try to push back death.
I agree. If things keep on going relatively like they are now, we all can have an indefinite length of life in our future.
Longer life means more time to think without having to learn all the things over that we had already learned. A new person has to learn it all first, before he can use it to think new things.
The question has to do with all the unforeseen things that might change the present status quo. One of these is that there might be a religion that is right, and a vengeful God might crush us for not believing in Him.