With the advances in technology from month to month, here is a logical guess on what the new PowerBook G5 should roll out with:
1.6GHz G5 chip.
(Less MHz than the desktop, so therefore, less heat, less power from the battery, longer batery life etc, etc, etc)
80GB Hard drive.
This is the biggest that Apple offer, and I can't see it getting any bigger in the near future.
ATI 9x00 Mobility Chip 128MB
Whatever the latest ATI mobility chip is out at the time.
4 x DVD=+R Slot loader SuperDrive
It's 2x at the moment, so you could make a logical guess that it will be 4x by Jan 2004. Also, with the ever increasing demand for multi-format drives, Apple has to offer this solution to the users. Personally, Apple will stick with the DVD-R format, like they have stuck with the one-button mouse.
Other:
two RAM slots.
Bluetooth
Airport Extreme
Backlit keyboard
Personally, I think that the G5 laptop will only be offered at 15" or 17" configurations, 15" at a stretch.
Apple might only offer the PB G5 at 17" due to heat issues etc, or as a sheer marketing aspects. Lets be honest, can you really see a 12" G5 PowerBook? Maybe in 2007...
Whatever the spec, whatever the MHz of the CPU, the PB G5 machine will sell and as tradition, demand will forecast supply.
I for one will be buying one. I just hope that it's not big and bulky...