Lastly, attempting to forecast "chance of immortality in the coming 60-odd years" is asking a question that relies for its answer on extremely controversial ideas. Particularly, attempting to answer requires us to forecast whether the rate of advancement in ageing research is speeding up or slowing down. This is hard, and can be affected by a bunch of different factors: funding breakdown in non-corporate research, Great Stagnation Hypothesis, breakdown in public acceptance of science, economic decline in some places, economic growth in some places, public uptake of anti-aging ideologies, attitudes towards the retirement crisis we're already facing even before anti-aging research comes in. Oh, and then we face the issue of whether we can or are improving our quality of scientific findings through better research training or data science/machine learning techniques. And then we get to the really out-there stuff "immortalists" are often secretly thinking of and can't stop yacking about: the chance that we manage to create Friendly Artificial Intelligence and trigger a Singularity, thus rendering us all immortal utopian transhumans before many of us on this board even hit retirement age.
TL;DR: I have no bloody idea, but I still regard contributing to my Roth IRA as a pretty sensible move.
EDIT: The one trend I'm willing to say I observe is that average life expectancy is a fairly good tracker of social and economic development, even once you've gotten over the infant-mortality hump. If you want to be immortal, you should encourage society to act in ways that result in longer average lifespans and also to fund anti-ageing research in hopes of achieving the fabled "ageing escape horizon" where medical science advances faster than you die.