I never thought of it that way, probably because I don't see the target markets as overlapping too much. The way I see it, there are two groups of people in the market for a new iPhone:
1. Those who want the latest and greatest, whether it be because they are early adopters of tech or they like to show it off.
2. Those who have accepted the yearly iPhone upgrade process as the norm due to carrier instistence and have no reason not to upgrade.
I would say the former group is more likely to go for the iPhone X, and the latter group would get the iPhone 8/8+. Not to mention, there is a significant cost differential, whether it be materially significant or psychologically significant.
Good breakdown. I have the 6 and am ready for some of the new features
I'm going for the X because of the bigger screen in the smaller form factor. I don't think I'd like the Plus.