I don't know whether this has been considered, or whether it's too late in the development cycle to do so...

What are the chances for a replaceable outer shell, as is common in the cellphone market? If it meant that the unit was a couple of mm larger in all dimensions, then that'd be an acceptable tradeoff IMO.

Then you'd just need to sell a couple of other shells to promote the idea, give/license the CAD/CAM files for the shell to a couple of the aftermarket cellphone shell suppliers, and Bob's your Uncle. Red, Blue, Silver, White, Carbon Fiber, wood effects, green with pink polka dots, you name it...someone will want it. If done well, it could become a major marketing win over the Ipod - especially since it'll especially attract the consumer that is less likely to be concerned about the technical wins.

I think that it's fair to say that the volume of these units that you can expect to sell will support such an idea.

The big question is whether it'd also be easy to replace the thumbwheel and buttons?