I’m not proposing that Apple will drop Bluetooth audio support from the iPhone. It’s there today and will continue to be there.
What I am suggesting though that they will not go with standard Bluetooth Audio as the solution for dropping the 3.5mm jack, but instead promote their own standard.
I think Apple was quite successful at getting companies to adopt AirPlay. Every receiver company is making AirPlay enabled receivers, including Sony, and many others. A quick search in Google showed me more than 50 A/V Receivers from all major brands with builtin support for AirPlay (http://bit.ly/2cdgZdU).
And just like A/V Receivers support multiple streaming protocols, I do see the same trend extending to headphones. So new headphones might support both AirPlay, standard Bluetooth and whatever other companies will come up with to try and compete.
You’re correct AirPlay today runs over WiFi and devices needs to be on the same network. But all of Apple devices already support peer-to-peer WiFi networks, so I don’t believe there’s a technical limitation on that front. However WiFi usage might introduce other issues, that Apple will need to overcome, like power usage that you mentioned.
More than anything this is wishful thinking. I do believe Apple has a huge opportunity to innovate in an area that has seen very little innovation, and actually fit their product line (Apple Music, Beats) and their “core values” — Love of Music, and appreciation to quality.