If they remove the headphones jack, the only decision that makes sense in a philosophical way is to cut with the past (pun intended) and go completely wireless.
Airpods will be included, while the upsell option will be a revamped line of Beats wireless devices, with a male Lightning charging port.
Color me completely disappointed if the default earbuds are wired (Lightning). That's not a signal of change.
Bluetooth adapters for headphones have been around for some time. The default ear buds will be wired to lightning and I suspect a 3.5 to Lightning adapter OR a 3.5 to bluetooth dongle will be included to make the transition less painful. The BT dongle will require recharging. One company at the west coast already makes BT dongles for wireless listening to the ipod or iphone. They were built for ruggedness and cost close to $40 a pop. I have one and it requires recharging. Apple will NOT be the first to go wireless with headphones. They already lost that momentum.
So expect Apple to sell a "premium" version of that around $50-60 when it really is the exact same thing as other dongles. Especially the AirPods which I think will be for the 2017 models, not this year. Apple cannot afford to screw the customers even more, especially in light of the EU tax decision and ' touch disease ' lawsuit.