According to Ming-Chi Kuo Apple will release an "upgraded model with wireless charging support" in the first quarter of 2019.
Kuo also added that an all-new design for AirPods is currently on track to launch in 2020. The AirPods, for now, are expected to get an upgrade to Bluetooth 5.0 and a W-series chip. The 2020 upgrade will feature an unspecified "all-new design" and Kuo also expects the revision to have "high integration with iOS and Mac products".
It sounds like Apple will fulfil its original promise of selling the AirPods wireless charging case as a separate add-on accessory for existing AirPods owners, and release a minor revision to the whole product at the same time – which includes the wireless charging case.
AirPods cost $159 and come with a standard case that requires a Lightning cable for charging, and Apple reportedly does not have any plans to sell AirPods with the Wireless Charging Case, so it will available as an optional accessory. So, if you want to have the Wireless Charging Case for your AirPods you will need to pay an additional $69 for this accessory. That takes you to a total cost of $228.
It is too expensive for so many accessories to have a wireless AirPod set, guess we will have to wait and see if Apple will surprise its fans with some crazy accessory that charges while you use your AirPods...