Small Cells is a great concept, and is being employed in different way till today with Passive approach. This passive approach loads the base station and creates possibilities of networking jamming mainly working as a repeater. Active small cells will really add to the reach of the base stations in terms of cost and space savings.
The idea that a lot of small cells could be used instead of a macrocell is interesting to me. Obviously this would create huge network management challenges. But it could really change the scale of investment required to expand coverage.