In addition to carrier aggregation, small cell deployment is also a priority for many carriers, seeking to improve network capacity and indoor coverage. There are obvious questions around technology choice (LTE vs. WiFi) and spectrum (carrier licensed vs. unlicensed).
LTE over unlicensed spectrum is increasingly backed by carriers wanting to maximize their control over the network and the quality of the user experience (ideally while minimizing spectrum cost). More than macrocell networks, small cell networks are deployed in a wide variety of circumstances: outdoors and indoors, in both public and private spaces.
In the background, we see a rapid proliferation of Wi-Fi, with device vendors, technology companies, consumers - and some operators - seeking to maximize their use of this ultra-low-cost technology. WiFi first is the norm for mobile data; it is quickly becoming the norm for voice and messaging too.