FYI, the main innovations of these kite sails compared to traditional sailing ships are that it doesn't need masts that get in the way of cargo handling and that it requires fewer crew. In other words, it's not faster or anything; it's just cheaper.
You also need vastly less sail area and the things are more reliable because wind gets quite a bit stronger and reliable at 100-300 metres up. The system actually isn't new. AFAIU main reason for it not getting wide-spread adoption is that shipping lines, not ship owners, pay for fuel.
Modern cargo ships are so huge traditional sails wouldn't provide enough force to push them around. Neither will these kites, mind you. But, supplemental energy will still be a bonus, and a kite can reach higher and sit in faster, more stable winds.