Apple could ameliorate this with the iPod Shuffle.
The Shuffle makes an excellent entry level device, and if they keep it around, they'll need a better way to interface with it. So why not take a note from the Apple Watch and allow it to be synced and managed by the iPhone, and other mobile phones? That way Apple can keep the price low by not adding a Touch screen. Since most people use it for workouts, why not add an accelerometer? And maybe a few more health sensors. It could also be used with chest straps, and other outboard sensors. Since it would have a BT radio, it could basically be used as an entry level Apple Watch, or Apple's answer to FitBit, all for around the same $50 price tag. And just like the old nano/watch trend, fitness straps could be used with it to wear on the wrist, encouraging a fitness band accessory market, just like the Apple Watch.
Currently, Apple can't competent with FitBit which currently has significant market share. So either they drop the price of the Apple Watch which does a lot more than just fitness monitoring, or they add some of the same functionality to a product that's already being used in that capacity like the Shuffle. Or, they just don't worry about competing with FitBit, and continue offering the Shuffle as a single function music player, or discontinue it with the rest of the iPod line in a year or two. Seems like a missed opportunity if the latter is the path they chose.
Apple doesn't really have an entry level Watch product, the way they have an entry level iPhone, iPad, Mac, TV, and currently an iPod. Once Apple eliminates the iPod line (Touch replaced by SE, nano replaced by Watch), the Shuffle will be the sole representative. In a world of multifunction devices, it's hard to imagine a $50 mp3 player being in much demand. And make no mistake the Shuffle has been $50 for years without necessarily adding any new features the way Apple's other products do. The Bluetooth radio is a must, and adding relatively minor features like an accelerometer will not affect their bottom line at all, and make the Shuffle more relevant to a broader market that isn't interested in the upsell to the Watch.