It gets really annoying to manually play and take out discs in a jukebox. I think that you should be able to hook up a hopper and put discs in there and they automatically play and then once the disc is over it goes out the other end into a chest. I have a screenshot of what it might look like. What do you think?
I think it would be better to use an interface for the Jukebox, where we could insert several discs, so as to have a "playlists", and an option directly added to the interface allowing to go from "in loop" to normal. (sorry, my english is not very good, I use google translation)
There is no need for a GUI or an additional useless block. Hoppers are a logical solution. However, the input hopper should be on the top (sides are fine ig) and the output should be a the bottom as ScotsMiser proposed.
I think hoppers would indeed be brilliant to support for jukeboxes! Even if nothing else I think having redstone power to a jukebox should let it loop infinitely. The fact that jukeboxes are completely manual is why I almost never even so much as give them a glance in any circumstance and might only use them for comsetic details, which is a pity considering their potential.