If Bluetooth seems to be main reason why it should be removed (the supply chain has already shown iPhone's cases with no headphone jack) why remove the headphone, we already use wireless headphones next to our hardwired headphones?
Going wireless with headphones is already here, so why remove the jack? To me the only reason is to drive sales, people will need a lightning adapter or headphones if they want a wired experience or carry around a dongle - so how is that for customer experience?
Say the headphone jack is removed. It was rumored Apple would provide the adapter/dongle for the customer, therefore, if this is accurate, it's not like Apple is thinking of making the customer purchase the adapter. And you would still have your wired headphones, no one is forcing you to purchase Bluetooth if You don't want it. I think Apple is smarter than this, if they do remove the jack, it could be for a grander unknown. But Apple is also not afraid to dare the unknown, as we have seen before.
If they remove it, It's likely other manufacturers will also. Motorola already has. Even if Apple chooses not to have it removed by the iPhone 7, I truly believe it will be removed in the next iteration of the iPhone. Ultimately, wires will be a thing of the past. But it will take time to phase away. Apple has a bigger picture and I don't know what that is yet, but soon to find out.
I think all this complaining and negativity has proven nothing, because Apple has confirmed nothing. Customers will be upset if it is removed, but I don't believe everyone will abandon Apple. Apple keeps everyone in the dark and it builds anxiety of 'What are they doing?' 'Why are they doing it?'
I guess we will know soon enough. But all we know is what's in front of us and those are rumors/leaks for the moment. Launch day will be the day.