I am going to wave my magic science wand and invoke quantum superposition for brain back-up. Your brain/mind/consciousness could be in a state of superposition with several back-up copies throughout the galaxy. If one physical body gets the axe, you just keep on going as the same person in a different place. Come to think of that, maybe it would make a good sci-fi flick. Good guy trying to hunt down several minds of the "bad" guy and kill them simultaneously.
Okay, more realistically, we don't know all there is to know about time, physics, the universe, consciousness, etc... so it is hard to say how long we could live.
I know that it is not good marketing to talk about "immortality", but it is a useful term when discussing life extension. It is a boundary condition. We use infinity in math all the time...no one freaks out about the fact that you can never count to infinity. Heck, we even use imaginary numbers...where is the outrage?!
Very good point, Mind, and it also isn't too smart for someone to generalize with regard to immortality and morality, trying to fuse the two into the same sentence completely takes away the individuality and concept thereof in respect to each person's lifestyle , movement, and goals - criticism should be minimized in that regard. If one looks upon a star and the star tells them they are immortal, some are going to believe, and then some are going to call them a schizo, and others are going to call them a drug abuser, and yet again, others will call them demon influenced, and yet.....where is perception in all of this? Where is individuality, it's this type of notion that hinders us and yet gives others a false sense of progression!
"Living indefinitely" is terminology for better marketing.
That could mean two minutes. Should be an easy sell.