I think Fiio and Hiby are the closest that exist today. They have dedicated hardware and physical buttons for the things listed in your comment. However, they do still ship with a custom Android OS and you need the touch screen to navigate your library and such. On the upside, this lets you choose your media library app. On the downside, it still isn't as good as the touch wheel on old iPods. I, too, am waiting for something like this to return. The Hiby is good enough until then for me.

Shanling uses a custom OS although it feels very primitive compared to iPods (e.g. the iPod Nano had VoiceOver for touch navigation). So I'm not really a fan of these dedicated single-function players; modern media player apps can be fast and convenient (more so than a clickwheel, honestly), and Android devices can still have dedicated control buttons. If only these devices weren't so bulky...