No question that life expectancy will continue to increase in affluent societies. The big problem for medical science will be how to subdue brain-function so that there are exciting and new things of interest spread evenly throughout the whole lifespan.
Perhaps the solution lies in developing a 'controlled' form of Alzheimer's disease so that stuff always seems to be new and interesting. This will test the patience of generation-x, -y, etc, but keeping great-great-great-granny amused will not be high on their agendas anyway. Taking this to a doomsday conclusion, in a thousand years time we could end up with a whole alphabet of generations competing for the same space at the same time [ and on the same medication! ].