When the chief executive of the Financial Times suggested at a media conference this summer that rival publishers might consider a “Nato for news” alliance to strengthen negotiations with artificial intelligence companies there was a ripple of chuckles from attendees.Yet Jon Slade’s revelation that his website had seen a “pretty sudden and sustained” decline of 25% to 30% in traffic to its articles from readers arriving via internet search engines quickly made clear the serious nature of the thr...