Sales dropped on ALL platforms when iPhone 6 and 6 Plus dropped but somehow, Sammy, Microsoft, LG, HTC and the like, continue to put phones on the market. Not because the iPhone had specs but it offered a different OS experience and a larger screen. It has ApplePay too but that is another post. Bottom line is, the only people a phone buying handsets with high end specs are those that know specs and that's it. That crowd is a minority of people buying smart phones and not the majority. I promise you. Most are not that deep with it.
I also suspect this is one reason Microsoft isn't going 24/7 high end is because the majority of buyers will NEVER use all it can do and will only be confused by the feature set. Experience kinda tells them that.
For instance, ask the average GS4 owner to show you how to get the phone the change web pages by blinking there eyes. Ask them if they ever use the hand swipe to change web pages. The GS4 has that feature but no one I know ever uses it and most can't set up its facial recognition to unlock the phone and most can't place a widget. Just because you have a "smart" phone doesn't make the owner smart anymore than a tennis racquet makes you a shoe-in for Wimbledon.
There will be no mass exodus from WP because another phone has specs 10 people out of 100 think they can't live without. If they go. they are leaving for a different OS experience, not phone specs.