Apparently Steve's posthumous roadmap focused on the idea that personal computers get 'smaller and closer to you' as time goes on. So the idea that an Apple Watch and AirPods could be all you need when travelling, etc. follows that premise.
I wish I could do this but I have yet to find a good Apple Watch replacement for owning and syncing music (rather than streaming it)
Is it not possible to sync MP3s to Apple Watches anymore? I have a really really old model, and I selected a few playlists on my iPhone, and when they change, the songs automatically sync to my Apple Watch.
There were back in the day. Apple really screwed up the development story for the watch as the initial watches just couldn't really do apps. They should have waiting for Series 3 before introducing apps and they still could do a lot to make things easier for devs.