Why bother to offload when your LTE is fast and unlimited? Growth rates seven years ago approached 100% as people first got iPhones. They are much lower now. Verizon last year saw about a 45% growth in data per customer, confirming a trend to lower growth in traffic. Cisco (and I) have been predicting this fall for the last three years because smartphones are now nearly ubiquitous. AT&T and others have been telling Wall Street that customers with smartphones were only increasing usage by about 40%. (Trends worldwide are similar but details deserve another article. Some charts below and at Cisco)
Technology in wireless is moving so rapidly that telcos could increase capacity 8-10X in the next few years without raising capex. They may not because they won't be able to sell so much data. Cisco projects a 7X increase in demand in five years, less than the potential capacity increase.