Yes, their solution is selling you an adapter.
Here's a simple experiment.
Go find the nearest person and tell them you are removing the headphone jack from their phone so they will no longer be able to listen to their music, unless they buy a new set of headphones or get an adapter they will have to carry around with them wherever they go.
See how well that goes over.
You will need D/A circuitry, which needs to be powered. Hence your adapter will need to have it's own battery or it will have to draw power from the phone. So, your choice is to carry this around or buy a new set of Lightning headphones.
Let me see...., a little plastic tab vs metal.... the extra force / leverage enacted on the port of the phone from an adapter.... you know, physics in the real world.
Ok, smart guy if your headphones are connected to the only lighting jack on the phone how are you simultaneously going to charge the phone, unless Apple adds an additional power port or you get a splitter?
I'm dying to hear your answer.
I take you have seen the MacBook, with it's single USB-C connector? You can't charge it and have anything else plugged into it a the same time, unless you use their $80 adapter that splits out into multiple ports. Same line of thought here, so don't think that Apple won't go down that road.
I know this will come as a surprise to you, but Apple in not infallible and they have been known to make mistakes in the past.