The Apple UK website is currently offering the iPhone Xr, the iPhone Xs, the iPhone 8 and the iPhone 7 available for direct purchase, with the iPhone 6 shown as 'available at authorised resellers'.
If Apple only sold the latest version, then it will cost everyone who want an iphone about £800.
Whereas a iphone 6s can still be bought for £299.
It would be a marketing disaster to only sell the latest model. Not everyone can afford the top of the range phone and not everyone wants the latest, biggest and fastest.
Have you thought about getting a refurbished one? My son bought me a refurbished iPhone 6 for Christmas and there’s nothing wrong with it, you can get different grades.
Apple no longer produce the Iphone 6 .. some retailers still hold stock though. It seems some of the last ones had problems with the cameras.
May well be time to move on to a more up to date alternative, or possibly search for a good secondhand model.
I have had two Apple Iphones. 5 and 6. Both a crock of ***e.. Over priced and over rated. I will happily go back to Samsung. The battery endurance on Iphones is useless.