I have a 6+, my 4th iphone. I have been on a strict and loyal "every 2 years" upgrade ever since the 3.
But I am not preordering the 7, and it's because of the lack of a headphone jack.
1. I don't use headphones often -- but when I do, I want them there and ready to go. Wireless requires charging, and I can't easily switch my jacked phones from my computer input to my phone input, which I do at work pretty frequently.
2. I am not into buying a new kind of headphone that I don't know if I like. I have a pair of Sure earbuds that I paid $300 for and I love them.
I think this is a bad move for Apple and it's probably time to short the stock, at least until they bring the jack back on the 8.