So you want to know what goodies will make up the g5, I will give you the best guess:
1st - What does the PPC Road Map say?
New Bus Topology/RapidIO Interconnect Architecture
32 & 64 bit (backwards compatible)
Symmetric Processing Capabilities
Part Number 85xx
What is RapidIO?? (www.rapidio.org
A high performance low pin count packet switched system level interconnect architecture. Applications include interconnecting microprocessors, memory, and memory mapped I/O devices in networking equipment, storage subsystems, and general purpose computing platforms. This interconnect is intended primarily as an intra-system interface, allowing chip to chip and board to board communications at giga-byte per second performance levels.
2nd - Speculation
A good guide to use is Motorola's first chip to include RapidIO, which is also a chip that falls in the 85xx numbering scheme. The MPC8540 is an integrated host processor with the following:
Dual Integrated IEEE 802.3 10/100/1G Ethernet
64-bit PCI-X controller up to 133MHz
333 MHz DDR memory controller
4 Channel DMA
Full duplex port connections at 128Gb/sconcurrent throughput and independent per port transaction queuing and flow control.
This looks very much like a nice little test bed for what will be on the G5.
As for the other stuff, I would guess:
ATA100-133 (tough call)
Definately DDR but what speed?
Will they skip to a double or quad pumped system bus?? Or does RapidIO eliminate the need for that??
My guess is you'll see a G5 in stores between Jan & Feb, I've got my money saved.