Yes it is true, that this improvement in the efficiency will add to the cost of the chargers as compared to the USB Chargers, but at the same time people will surely go for at-least one of this kind to enable them their fast charging needs in emergency conditions.
I would be more certain that this will take off if it weren't for the standardization of power cords on microUSB. Granted, they are a minor irritant when you get them upside-down (seems like at least 75% of the time) but that is a lot better than having a separate and expensive unique cord for each device. I was surprised to see up to 88% efficiency, but the flip side is that I can only charge on a wireless station. USB power cubes are cheap enough to just buy several.