It uses Siri, which needs the internet to work. So any Siri command will require the internet.
You can still adjust the volume with the physical controls on the phone, and switch tracks with the on screen controls.
An extreme example of a dev abandoning an app would be the Monster Hunter app by Capcom. Back when iOS 9 dropped, it introduced a bug where Monster Hunter just wouldn't launch at all. Unfortunately, I can't find an archived version of their release notes (the only one thats been archived is from 2014 [0]), but Capcom basically said "This app does not, and will never work, on iOS 9". Under Apples old rules, this was cool. No worries. But under the new rules, this app would be removed immediately.
I don't think apps should be removed for having non-retina assets, or not supporting 4.7" or 5.5" displays. But if the app truly doesn't work anymore, and hasn't for a while, then I would consider that being abandoned. Even then, Apple will be working with devs to try and get the issues sorted
>"We are implementing an ongoing process of evaluating apps for these issues, notifying their developers, and removing problematic and abandoned apps from the App Store. " (from the email sent to developers)
Edit: re-reading my comment, it does sound a bit sarcastic. I want to make it clear, I actually did set this to my homepage! :-)