Apple is certainly a market leader, but that doesn't mean everyone is going to follow them off the cliff. Sony introduced so much proprietary nonsense after the success of the Walkman, and look where they ended up.
I firmly believe that if Apple eliminates the 3.5mm headphone jack, there will be a noticeable drop in iPhone sales/estimates. Apple is eliminating one of the most universally used ports without offering a compelling alternative. Why would anyone want to pay a premium for that?
Oh yeah I don't disagree with that. It'd be like Apple dropping USB from their Mac lineup for something proprietary.
I have no desire to switch right now. I just ordered Bose headphones on Prime Day via Amazon so I'm all in for the 3.5mm for now.