"Hey Siri" support and possibly wireless charging case alongside AirPower charging mat.
KGI: Apple Developing High-End Over-Ear Headphones, Launching Late 2018 at the Earliest
Apple to have own-brand, high-end over-ear headphones with all-new design; to be as convenient as AirPods with better sound quality; shipments to begin 4Q18F at earliest; Primax & SZS will be the key suppliers & will benefit from high ASPs. We believe that after AirPods and HomePod, Apple’s next addition will be high-end over-ear headphones, making its acoustic accessory lineup more complete. Existing suppliers Primax and SZS will be Apple’s partners on this new product. Primax will receive assembly orders on its familiarity with the acoustic business, and SZS is likely to use MIM technology advantages as leverage to become the exclusive or main MIM part supplier. The new headphones will be priced higher than AirPods and should help boost the business momentum of Primax as the assembly provider.
Kuo's prediction on upgraded AirPods follows a similar report just a few days ago from Bloomberg. Kuo says the new AirPods should launch in the second half of this year.
We think the main difference of the upgraded AirPods, which won’t look much different from current AirPods, will be the wireless charging case and the adoption of an upgraded W1 chip. We believe that the charging case will adopt different processes for the external appearance and to meet thermal requirements from wireless charging, the hinge price will rise 60-80%.Beyond this year's update for the AirPods, Bloomberg claimed this week that Apple is working on a subsequent AirPods update that would bring water resistance to the earphones, but that model wouldn't arrive until 2019 at the earliest.