And this is likely the reason for the reportedly low sales of the 8. I was surprised when they announced both at the fall event as it seemed obvious the X would cannibalize sales of the 8.

The iPhone is already a expensive premium phone, why bother with incremental changes of the 8 when the cool and shiny X is right around the corner.

It's also strange to me how they offer two new phones with different feature sets. Usually when Apple introduces a new device with a controversial change (e.g. USB-C only on the 2016 MacBook Pro), they don't offer a updated device without that change. It can be perceived as a lack of faith in the new product.