That means that everybody who is already living now will die in the next 103 years.
If at the moment 7 billion people live on earth practically all will die in the next 103 years. That their individual life expectancy is 80 years doesn't change the fact that practically nobody (that is, to the error of 0.5%) survives his 103rd year.
I started with the US data. If we'd adjust it for the world, we'd see that even for life expectancy of 67 less than for example 10% of those living now will survive their 80th birthday or something like that. So the rougher approximation is that you have to increase the "67 years" some years more but anyway in 100 years practically everybody living now is dead. Yes he was not technically right with using the life expectancy of a single person to give the exact year, but the "cutoff" year is still not much farther away. And how old are people now actually matters to know how many will die in which period.
But: zero of these 100 people live more than 103 years (if we started with 1000 only 3 would live to be 103 years old):
http://www.ssa.gov/oact/STATS/table4c6.html
That means that everybody who is already living now will die in the next 103 years.
If at the moment 7 billion people live on earth practically all will die in the next 103 years. That their individual life expectancy is 80 years doesn't change the fact that practically nobody (that is, to the error of 0.5%) survives his 103rd year.
I started with the US data. If we'd adjust it for the world, we'd see that even for life expectancy of 67 less than for example 10% of those living now will survive their 80th birthday or something like that. So the rougher approximation is that you have to increase the "67 years" some years more but anyway in 100 years practically everybody living now is dead. Yes he was not technically right with using the life expectancy of a single person to give the exact year, but the "cutoff" year is still not much farther away. And how old are people now actually matters to know how many will die in which period.