"The new program’s cost to Sprint is minimal" NYT reports from CEO Claure. Reporter Cecilia Kang adds, "It doesn’t require additional network upgrades; instead, it would be the equivalent of adding more cars to a highway, the company said." That's an exaggeration, of course. Sprint may have the emptiest network in America, but some of their $3B capital budget is required for the congested areas.
The cost of bandwidth, even on mobile, is low and getting lower rapidly. A recent EU study found fully loaded cost often one euro/gigabyte or less. Consultant Antonios Drossos emails, "the actual incremental cost of mobile data which depending on the network topology, configurations, vendor pricing etc ranges from €0.05/GB to €0.5/GB."
Drossos is more likely on target. Free in France and several in Scandinavia are selling 50 gigabytes+ for $22. Even if we assume people only use half their allotment, that's 80 cents retail for a profitable product. Ambani in India is selling 10 gigabytes for $7.40.
David Small of Verizon estimates the cost per bit will go down 30-40% per year, confirming what I’ve written about the efficiency of carrier aggregation, advanced LTE & MIMO. That’s a drop of about half in two to three years and three quarters in about five years.