Re: BMW should stop selling the 7 series because they sell more 5s and 3s using that logic.
Not really the same thing is it. They didn't come out with the 7 as a replacement for the 5.
For your comparison to work BMW would have to be currently producing two models of the 7, one from 2 years ago and one newer, slightly bigger more expensive one. If that was the case, and customers preferred the 2 year old model to the current one, they you'd be bang on the money!
It's not the case though is it. Apple released the X to replace the 8, but customers prefer the 8. That's all this story is saying.