According to this report from the Wall Street Journal, Apple is planning to use USB type C across the whole range of iPhones this year.
Apple has traditionally used proprietary connectors on its iphones. The connectors used to be fast, but with USB type C the industry standard is certainly faster. Maybe the Cupertino giant has decided its time to stop devoting resources to duplicating functionality? After all, Apple engineers helped develop the standard.
Users had become accustomed to using the lightnig on iPhones. Apple faced a lot of criticism for adopting USB type C on the new MacBooks, as you needed a dongle to connect an iPhone. This could be set to change, if the rumours are true. At least, one less adapter for you.
Apple rarely follows industry standards. On the iPhone 7 they ditched the standard 3.5mm headphone jack in favour of the lightning connector. Now this report claims the port is going the way of the thunderbolt.