A new image of a purported iPhone 7 part over the lightning port shows up. And if this image is true, at least one iPhone 7 model will still have a 3.5mm headphone jack. You can clearly see one in the image.
This morning, French site Nowhereelse.fr shared an image of a Lightning cable assembly, apparently destined for the iPhone 7, which differs in design from the same part found in the current iPhone 6s.
The assembly part is host to a number of components, including cellular antenna cables and the obligatory Lightning port, but the new design clearly shows a separate white headphone jack on the far left-hand side.
Personally I still think that at least one model will not have a 3.5mm headphone jack. Maybe its the rumored iPhone Pro that will not have a headphone jack, but have a Smart Connector, dual camera and Apple Pen support?