"Hey Siri" support and possibly wireless charging case alongside AirPower charging mat.
Discontinued AirPort Extreme and 2TB Time Capsule Finally Disappear From Apple Online Store
At the time the accessories were discontinued, Apple said that it would continue selling existing stock until available supply was exhausted. It appears that point has been reached for both the AirPort Extreme and the 2TB AirPort Time Capsule, which have been removed from the Apple online store.
There are no longer any AirPort products available for purchase from the online store or Apple retail locations, with the exception of some refurbished AirPort devices that may continue to be available on the refurbished site.
Apple had not updated its AirPort products since 2012 (Express) and 2013 (Extreme and Time Capsule), and rumors in 2016, which ultimately turned out to be correct, suggested Apple had stopped development on the product with AirPort engineers reassigned to other devices.
In lieu of its own line of AirPort products, Apple is now offering third-party routers like the Linksys Velop mesh Wi-Fi system.
Apple's AirPort base stations provided some unique benefits that are not available through third-party options like built-in Time Machine backup support in the Time Capsule and AirPlay functionality for the AirPort Express.
Though the AirPort devices have been discontinued, Apple plans to provide service and parts for the current generation models for the next five years.