Here's my prediction:

Roland G80-X - start with the G70 and:
+ mp3, mwa, wav, playability
+improved OS to accomodate above and possible edit features
- 5 lbs.
- floppy drive AND PCMCIA slot
+ 2 USB slots for memory storage and OS updates
+ color touch screen
+ new Fantom X piano samples
+ 36 MEGA instrument samples for guitar, strings and horns
+ a large bow to V-synth technology (again)
+ 3 LIVE drum sets
+ all new styles; still not enough US rock stuff; more world styles

I'm sure I'm missing something. Anyone care to continue...