The HomePod will be an accessory.  A watch is an accessory.  A phone is an accessory if you take a wide enough view.  The AirPods are a new product for Apple.  They also ushered in a new product category that their competitors are already racing to copy.

And Apple will be just fine.  The AirPods have made more money for Apple in 8 months than a lot of their competitors make all year.  And yet that revenue is basically a rounding error on Apple's balance sheet.