I'd doubt it will happen, a big part of apples selling point for the ipod is the exclusive use of itunes and the itunes music store, also it builds brand loyalty as like you when peoples ipods break, they have all this music purchased in a format only ipods can play, therefore increasing the likelehood they'll buy another ipod, thereby lining apples pocket again.
It will be interessting to see what happens with microsofts zune project, and the rumours they might offer free duplicates of customers itunes purchases when the zune products are released.