I'm most excited about automated agriculture, they've already successfully prototyped many robots that can do things like pick fruit /vegetables, milk cows and so on. It could be as soon as 20 - 30 years that we see food costs in first world countries drop to 1/10th of what they are today. As the cost of goods is just raw resources + human energy and when the raw resources is only the cost of the land (+ setup costs and maintenance which will eventually be dirt cheap too) the final product cost will drop dramatically.