My guess is that the first customers for this cable will be in the finance industry. A 30% improvement in latency doesn't matter much for the layman, but in finance, it can mean significant amounts of money. Already, an enterprising trader constructed a more direct line from Chicago -> NYC [1]. Going from 16ms -> 13ms was apparently worth $300 million. This fiber could bring a very large profit if you had exclusive rights to it via a patent. You could execute guaranteed-to-profit arbitrage strategies between any two markets if you were willing to build out the network. And no one could compete with you for a whole 15 years!
[1] http://www.forbes.com/forbes/2010/0927/outfront-netscape-jim...