LONDON (Reuters) – More than half of babies born in rich nations today will live to be 100 years old if current life expectancy trends continue, according to Danish researchers. Increasing numbers of very old people could pose major challenges for health and social systems, but the research showed that may be mitigated by people not only living longer, but also staying healthier in their latter years. “Very long lives are not the distant privilege of remote future generations — very long li