You must be new herelol
99% of these people that say it won't sell well/they won't buy/touch ID on the back is stupid are going to buy it.
When Apple first introduced touch ID on the iPhone, this forum was filled with threads about how it wouldn't work, Apple would steal the fingerprint etc etc
Good points. I find it to be one of those things that it's just an uncertainty that iPhone users aren't sure if they're going to like it or not, because they either have no experience with it or they just don't like the idea of Touch ID being remapped.
I will say some of the Android users I have spoken with, actually have grown fond of the finger print sensor on the back of the Galaxy S8 and they said it has not has been much of an issue as they thought originally it was going to be. I believe There will be a demographic that will either purchase the iPhone regardless of where Touch is placed or some who will completely Shun the idea.
Either way, this Keynote will be highly anticipated come September.