Well Rob did say a while back [shortly before the Rio 10S and 30S were announced], that they had done with flash-RAM based mp3 players for a while.

[and were therefore moving on to other kinds of audio devices for SonicBlue].

Rob, wouldn't say anymore, but I can guess we can safely assume they are working on a new hard disk player to replace/supplement the Riot.

I must say, barring looking at the UI and usability, the Nomad Zen does look pretty neat, esp. when compared to the 10+ months old Riot -
The Zen is pretty pocketable - no edgy corners to stick out, the Riot not so pocketable.

So, yes its high time SB revamped the Riot.
I only hope I don't have to wait until Jan next year to see one!