I think, if the empeg were to come out today, it would definitely do better than it did the first time around, however the 10mbit Ethernet clearly wouldn't cut it, and normal users would probably want a simpler and more automated interface for moving tunes back and forth.

The main issue the empeg would have is the general hostility of many new cars for aftermarket audio products. In far too many new cars, there's just no easy way to add your own stereo. Like it or not, I'll bet the future is more likely to have cars with some sort of docking solution for iPod/Karma/etc.