It may not only be the iPhone 15 that receives USB-C. Apple may also consider upgrading its current iPhone 14 and iPhone 14 Plus models to USB-C.
The latest tvOS 17 beta reveals that Apple has six unreleased iPhone models, of which four have been identified as iPhone 15, iPhone 15 Plus, iPhone 15 Pro, and iPhone 15 Pro Max.
The remaining two models have been identified as new variants of the iPhone 14 and iPhone 14 Plus, with the introduction of a USB-C port likely being the only difference compared to the existing iPhone 14 and 14 Plus.