Fair enough, and an understandable point of view from someone who doesn't follow Apple closely. I'll expand on why I don't believe USB C will be in the iPhone 7-9 (including s models)

Announcement of the Lightning connector, Phil specifically states it's a connector for the next decade. https://youtu.be/h7Qtp6Iv7a0?t=36m5s . First iPhone with it was the 5, and now up to the 6s has us at the start of the 4th year of a possible 10 year possible lifespan. This could of course change, and Apple does change it's mind at times.

Another aspect is Apple using the proprietary connector and Made for iPhone labeling as a way to help increase ethical manufacturing of accessories. Any certified device has an authentication chip in the lightning connector that is only sourced direct from Apple, and the entire supply chain for the accessory manufacturers has to adhere to these guidelines.

Between those two factors, and seeing Lightning now appear in more then the phone and tablet, it's my belief that it's going to be around for a while.