I think that we might find ways to slow the aging process medically – a lot of scientists work on research to help us age healthily – which would probably interfere with any evolution to live for longer.
Evolution is based on natural selection of those with the ‘best’ genes for survival, but intervention by healthcare means that almost everyone can potentially live as long as people with genes that predispose them to living longer – so there’s no selection process for these genes to be passed on more than others. This is also why genetic diseases that we can treat (and so don’t affect people’s ability to live long enough to have children and pass their genes on) can be relatively common in society – there’s no selective pressure against these genes!
We do live longer not than we used to hundreds of years ago, but its hard to say how much of this is due to evolution and how much is due to better healthcare, diet and overall quality of life!
It is possible that humans will continue to live for longer and longer, but I think it’s unlikely that we will ever stop aging at all – the longer we live for, the more things could potentially go wrong with the cells, and we’ll probably encounter new aging problems that we’d never considered before.
As far as current research is concerned, its more important right now for us to focus on helping people age healthily than finding ways to live longer – it would be rubbish to live twice as long as we do now if aging diseases still started affecting people at 40 – 60 years old!