Keurig Green Mountain Inc's thrust into the home-brewed cold beverage market, once seen as a potential game changer for the single-serve coffee machine maker, faces increased skepticism from investors worried in part about waning consumer enthusiasm for soft drinks. Keurig Kold, which will make everything from craft sodas to iced teas, is expected to launch in the fall, entering a space dominated by home-brewed cold drinks market leader Sodastream International Ltd. Keurig has heralded the new machine as giving it access to a $50 billion market for cold beverages in the U.S., five times the size of the hot drink market.