There's rumors that it won't have a headphone jack. I really hope that rumor isn't true. I want to be able to listen to music and charge at the same time.
If your charging it shouldn't be an issue. You can also get a battery case or those travel battery packs.
The sound quality of Bluetooth audio sucks; it's fine for voice calling on wireless headsets, but listening to music is painful. Apparently there is a high-quality BT audio standard, but as of now, Apple doesn't support it. Frankly, I would have considered switching from Android to iOS with the iPhone 7, but if it lacks a headphone jack, that'll put a damper on that plan. I'm not privileged enough to have one of those newfangled cars with Bluetooth capability in the stereo (which, again, still sucks unless both the stereo and Apple support the aptx codec, which at least Apple doesn't), and if I can't charge and listen at the same time, well, sorry, but no deal, Apple.
Flatulentius, my car doesn't have Bluetooth either... I ended using an FM transmitter adapter, connects to the iPhone with the Lightning connector (and plugs in the accessory/lighter to charge at same time). Not perfect quality but quite tolerable (better than the earphone to fake cassette deal I used in the previous car). Why are they doing this? Well partly to drum up demand for new accessories, likely. With portable devices, it's also getting to the point where the size of connectors does limit how much smaller they can make the devices (remember the older 30 pin connector?) - similar reason why the new Macbooks don't have a built-in Ethernet connector, and you need to use a Thunderbolt-to-Ethernet adapter.