Apple is rumored to be considering a 14 inch Macbook Air, which would likely appeal to the Asian market, as 14 inches is the standard screen size in many Asian countries including China, Digitimes reports.
Sources from the upstream supply chain also claim that Apple is turning its attention away from the West to focus on Asia, specifically China. According to Digitimes:
Currently, 14-inch panels are the mainstream specification of the Asia notebook market, while consumers in Western countries prefer 15-inch models. In the global market, 14-inch models have an about 20-25% market share, but in Asia, the market share is about 35-40%, an indication of Asia consumers’ fondness for 14-inch models
I would advise not to take these rumors that seriously, as Digitimes have a bit of a reputation for supplying false rumors. However this one does seem somewhat plausible, even though it is unlikely that Apple would carry three different sizes. A 14 inch model would no doubt replace the current 13 inch model if it were ever to be released.