MP3 has caught on, so much so that a future replacement technology has not been identified yet. MP3 is going to be around for awhile -- at least 10 years, says iSuppli analyst Shyam Nagrani. It will overtake the CD format, too, he believes.
At this point in time I can not see why you would want to replace mp3, that is unless you work for the RIAA. There is no DRM with MP3 that's why it is so popular with the people, If MP3 goes away it will only be for one of two reasons something better comes along or the RIAA some how forces it to go away.