Basically the project would have a hard drive supplying a lof of storage (an IDE hard drive could be use, or maybe SATA with some usb adapter), and a big touch screen for the control.
A big effort would be done to design a really good interface with a lot of features and capabilities.
In a second version, internet connection could be provided, which still would increase the music posibilities. Keyboard could be used but it would be hidden in the jukebox furniture.
Superb sound quality would be a must, effort would be done in the digital part (additional codec?) and in analogics (good design of the amplifier circuit and godd integrated loudspeakers)