Apple already thought it through when they added lightening port on iPhone years ago. The current case is not of adding value, but removal of accessibilty.
Right -- Apple is so greedy, that despite losing market share and reporting their first losses in 13 years, they're going to remove a universally adopted audio standard from their phones giving their competition a huge edge, when they don't have to? Better sell all of my stock now then.
And yet in hi-fi gear the DACs are never put inside the speakers and the amplifiers are rarely put there either. The chance that head phone manufacturers will use better DACs than the ones in iPhone are very low. Sure, the ones in expensive ($300+) head phones will probably be better but the vast majority of the head phones will use dirt chip DACs.
What are you talking about? How do you think BlueTooth speakers reproduce any audio without a DAC and amp!? How do you think my AirPlay and BT Denon capable amp reproduce any audio without them? And how do you think home theater amps with digital optical inputs, which have been a staple for years, reproduce audio without a DAC? You clearly have no idea what you're talking about. Not even worth addressing your other points -- but, if a manufacturer cuts corners, they will lose business. Period.