Heh. Armchair quarterbacking at its best. 7 years of stories doesn't necessarily mean 14 "APs", which is kind of a meaningless term for a product anyway. WotC has been story focused for quite some time now, this isn't new with 5E. Almost the entire 4E cycle had story arc after story arc that drove the organized play and was mirrored in the novels, video games, and to a lesser extent, the main RPG line. Each "story" could be delivered in all sorts of ways over the next 7 years, and WotC is hardly locking themselves in to a rigid product schedule extending almost a decade.
The first 5E story arc, Tyranny of Dragons got two RPG products and tons of tie-ins. The second, Elemental Evil, gets one RPG product and tons of tie-ins. Not much of a precedent has been set yet, and Mearls has already stated that they are experimenting with the best delivery. The third story arc could have a very different release strategy, as could the next after that. And how many "stories" we'll get each year just might vary also. And it doesn't mean we won't get books that aren't tied to the story arc du jour, like a Deities and Demigods or Manual of the Planes.
And, if need be, what's stopping them from swapping the 2016 fall story arc with the 2017 spring story if they need to change things up? Or dropping a story arc, or adding a new one in?
While we of course don't know what the future holds for D&D, I'm not worried in the slightest. I've had fun with every edition since 2nd, and I'm sure I'll continue to play, have fun, and buy new products for many years to come.