Unless Apple decides to ditch the port entirely in the near future, your argument doesn't make sense.
Sure, there will be some minor pain during the transition, but the world did not end when Apple transitioned from the 30-pin to Lighting transition, nor did it end when phone manufacturers transitioned from micro-USB to USB-C. You can use USB-C to lightning adapter, like how they have 30-pin to lightning adapter earlier.
Nobody will throwaway their lightning accessories. iPhones and its accessories have a strong used market, and it will find good homes to older iPhone users.
Does no one remember the uproar when Apple first introduced Lightning? Everyone I talked to hated that their old 30-pin connector cables wouldn’t work anymore. With how much more popular the iPhone is now compared to over half a decade ago, it’d be even worse.
I'm always confused how people talk themselves into believing this. It is obviously not the case.