Recently, many in the Mac community have been discussing the possibility of a G5-based Cube design, similar to Apple's Power Mac G4 Cube. I don't think this will happen, as the thing that killed the original G4 Cube, and that would damn the G5 cube to the same fate eventually, is the lack of market for the thing. Yes, I would like to have one, but being a Mac geek is not a characteristic most Mac users share. Let me explain the lack of market for the Cube and why it's destined to fail.
The Power Mac G4 Cube was 8"x8"x8" masterpiece of space efficiency. It was a powerful system; especially considering the space it existed in. But it was also a powerful system with no expansion capabilities. For years Mac users had been clamoring for a low-budget headless iMac-like device, and the Cube almost met those requirements. The premium of a PowerPC G4 processor was not one of the things that had been asked, even though it's safe to assume that people like power. It was that premium, however, that killed what the Cube could have been.
Apple had a headless iMac G4 well before it came up with the real iMac G4 much later. Apple had answered the calls of something small without a monitor, but they flubbed up when they included a G4 and made the Cube unaffordable: At the time of its release, as is true now, the G4 cost a lot more than any G3 chip. Professionals had little interest in the Cube due to its lack of expansion.
So, where was the Cube meant to go? Into the homes of the old NeXT fans, Apple aficionados, and the niche of people who wanted a workstation and knew that they would never, ever need to add anything to it. In short, the market for the Power Mac G4 Cube was virtually non-existent and it was doomed to low sales figures before it ever made it out the lab. Perhaps Apple expected this, but publicly Apple had been pushing the Cube and then stated regrets when they killed it — Apple has been known for its marketing blunders before, if you can believe that.
Before Apple prepares the Power Mac G5 Cube, maybe they should take a look at the 20th Anniversary Power Mac and look upon the project with a very limited lifecycle. Already the G5 Cube is hobbled more than its predecessor was: heat considerations over the G4 will require more R&D effort to overcome and maximum RAM will be severely hobbled from the current platform's 8 gigabytes due to space considerations. R&D costs would outweigh potential profits at this point, but Apple has a few other roads to take if it's dead set on a Cube.
IBM's PowerPC 750GX processor, with 1 MB L2 cache on the chip, running at 1 GHz and up, will be a performer. Folks who don't need the Velocity Engine and already have a monitor would be the perfect target for the system. Development costs wouldn't be so steep since Apple has worked the G3 over for years. If Apple wants AltiVec, they could wait for IBM's successor to the 750GX, the VX, which is rumored to have the Velocity Engine but still beat Motorola's G4 in the space and heat departments. Such an economy system could go for well less than anything else Apple offers and could just be Apple's first true foray into the budget PC market, nudging aside Windows competitors in the $700 and lower price range.
If Apple wants to move far and away from the G3, which it seems to of late, then the latest G4 processors from Motorola would be apropos. They're smaller, faster, and cooler than the G4 that Apple used in original Cube, have on-chip L2 cache, and run Mac OS X more than swiftly. Of course, Apple isn't likely to repeat history, so a G4 Cube Mark II isn't likely to happen either, as easy as it would be to update the old design for a minimum of effort. Customers may avoid a system because similarities to the old Cube, dooming it even more than it might be before it ever reaches shelves.
Since Apple likes to push itself and not rely on old technology, making a G5 Cube would still be the most likely move for Apple, just a very difficult one. They must realize that such a system has a limited market and should in turn expect a limited life cycle. It would make a great Mac to commemorate 20 years of Macintosh, and with Panther's darker, metallic look, this could be a great opportunity to return to the black cube motif of yesteryear and allow Mr. Jobs a true revitalization of his dream machine of almost two decades ago. But even that scenario sounds like a dream.
The Cube carries with it a Biblical metaphor: It will return one day, but no one knows exactly when that day will be. Nothing tells Apple to concentrate on a product more than sales, and the chorus of Mac geeks clamoring for Cubes is infinitesimal by comparison. Mac users need to remember what killed the last Cube and realize that things have evolved in a manner that would only complicate development of a new one. There are plenty of Mac lines out there with healthy life cycles and established market interest with something to offer to everyone. Rest assured that the reality of Apple's product line is more than good enough to serve us even without a Power Mac G5 Cube.