The historical data mining and analysis is something computer used to take into account while giving different scenarios and then it was upto humans to make sense of the results, which sometime can be very complex and can take months for humans to conclude. I think Watson will replace the human intervention to a bare minimum so that the decision time can be shortered.
I think in five years Watson will be engaged by Pentagon for developing war strategies. This is one area no one is thinking about. If they have this massive insight about life, it is possible Watson will get some generals to early retirements.