The footwear and athleticwear giant is going through a transition.Nike (NKE 0.07%) has dominated the sportswear industry for more than a generation, but the sneaker king looks surprisingly vulnerable these days.Revenue growth has ground to a halt, and the company is backing away from its direct-to-consumer strategy, admitting that it made a mistake in turning away from its wholesale relationships with retailers like Foot Locker.Indeed, its revenue has been contracting -- it was down 2% in its fiscal fourth ...