This idea struck me as a cool one a little while ago.. If apple feels that tha all-in-one market is essential, why not sprout a new version of it?
Keep the emac design, maybe restylize it a bit. Change the mount for the motherboard to hold a new design where the analog board is seperate (not sure if it isn't already)..
Now, make a sub-ATX board, socket the cpu and maybe the video chip (hey a company selling video chips could be cool), keep the power supply in a seperate box and make the board have external DVI and a VGA plug that switches with the emac's internal display..
The switch? Now make a new model eMac. eMac XT maybe - a small upgradable tower that uses the exact same board, 2 sats HD slots, a combo/superdrive slot, and maybe even a PCI slot that's simply not used on the classic emac but still present..
What you end up with is two varieties of machine, perhaps for the same price. Both able to drive dual displays (not that they don't already, duh), and both rather upgradable.
That done, make an iMac XT as well that has an AGP slot and other goodies the emac XT could only dream of having.. except they both use a similar board. Now you have 3 models using the exact same board, 2 the same power supply and well yeah.
For distinguishing the eMac could be white plastic and the iMac metal like the g5. It'd be spiffy and perhaps even sell some.