It is no secret that the iPod is a diminishing brand for Apple, with sales dropping and the iPod not being promoted as it once was. It is fair to assume that the iPod certainly needs a reboot to become great again.
The issue here is the iPhone has a build in music app, a device most Apple fans will already own. So is there much need for an iPod touch with an iPhone already in hand? Perhaps an iPod Shuffle would be useful for joggers and maybe even the iPod Nano if you require Bluetooth capabilities. But one iPod stands out from the rest, that is the iPod Classic which was discontinued around 2014.