"Hey Siri" support and possibly wireless charging case alongside AirPower charging mat.
AirPods and AirPower: Everything We Know
Apple Solves Yield Issues with Apple Watch Components, Mass Production Now Slated for January Claims Report
The report notes that this is due to Quanta increasing its number of employees from 2,000 to 10,000, as the company expects to hire 20,000 employees to help with production. Apple is projecting to ship a total of 24 million Apple Watches in 2015. The United Daily News also mentions how a new "iPhone 6s" will likely miss a Spring debut, but that is to be expected as production of a new A9 chip has yet to gear up. The launch would also be unlikely as Apple's iPhones have never launched in the Spring.
Employee comments made after the Apple Watch's debut in September noted that Apple may not be planning to launch the device until February 2015 or later, as the company originally planned to have the watch ready to ship in time for the 2014 holiday season. However, it is now possible that Apple has solved many of the issues surrounding production of the Apple Watch and will make its "early 2015" release projection. When it goes on sale, the Apple Watch will be available in a variety of materials with several different band choices and start at $349.