Until all those customers already have their models and aren't thinking in upgrading any longer, which is exactly what is happening.

And that’s why Apple is focusing on service revenue and ancillary devices like the Watch, AirPods, etc.

What tech company has a better,more profitable business model than Apple? Even long term, the only two other tech companies I would bet on are Microsoft because of Azure and Office (definitely not Windows) and Amazon because of AWS and to a lesser extent the stickiness of Amazon Prime.