Basically, what the scientists will do, in their attempt to extend human life is solve one small problem at a time until the accumulation of small solved problems ends up adding years to our life span.
I question whether they will be allowed to do more than make life more functional. I tend to be doubtful that God will allow any major gains in this area before ending things.
We have already more than doubled the lifespan. But, regardless of the medical advances, there is a limit to how much more we can extend life. Immortality is not likely.