Will customers bite? Yesterday’s event in San Francisco unveiled the predicted suite of new iPhones, a large-screen iPad Pro and a revamped Apple TV. But one juicy tidbit had been kept under wraps: a monthly payment plan designed to get users into a new phone every year. The iPhone Upgrade Program, unveiled amid a market shake-up in cellular contracts, allows folks to purchase unlocked phones directly from Apple, with free annual upgrades. The new offering signals that tech-hungry consumers are increasingly losing their appetite for two-year phone plans.