For kinetic energy, I was thinking of it more as an extra source of energy. We will still have many other sources of energy but lets say you were going to shop and were walking around then you would be charging up your phone at the same time. This would reduce costs and allow energy to be used where it is needed such as for those who are disabled.
I also think thermal heat could be a good source to help reduce costs in the future.
Moving your body to generate power makes more sense for running low power sensors or some LEDs than charging an android or iPhone. It takes several watts to charge a phone and that should be a continues stream of power. I'll have to find the numbers to do the math for kinetic energy harvesters but it seems to me that the body movement activity to sufficiently charge a smartphone would be closer to vigorous dancing than casually shopping. A typical electric wheelchair motor is 250 watts so it uses roughly the power of 100 smartphones when operating.