Indeed, the high falutin' IFE systems are (almost certainly) already past their peak. It will be far cheaper to provide material for access via USB, using a tablet or SmartPhone. With a WEB front page and menu options as to what to see/listen to, it will be possible to change the systems very much faster than at present. As Paul Wilson says, the server hardware and absence of all the screens and heavier cabling will save weight.
As we have already read, the LCCs will lead the way with this. But it is going to be driven by the generational change of the pax.