I'm a waiting switcher. The iMac is basically almost there for me, except for still having the G4. Not only that, but not even the newer, 512K L2 cache version. This is likely due to low availability all going to PowerBooks, but it is just one for thing that keeps the higher-end iMac from being a really awesome machine that it can be. Since it is not expandable other than RAM and AE, it needs to come with good stuff. The G5 at even low speeds should be in there tomorrow - screw the PowerBooks.
The damn Apple product pecking order has to go. The idea that processor power has to monotonically decrease down from the top Powermac, through the PowerBooks, then the iMacs, eMacs then iBooks is not good when you need some flexibility. This really constrains when model updates can happen. I think people don't expect laptops to have the fastest CPUs for power and heat reasons. Allowing the top iMacs to at least have the same CPUs as the PowerBooks would be reasonable. However, given the G4 situation that's stagnated for so long, this has now become unacceptable. Apple has to go G5 across the board as soon as posible. This means that if the PowerBooks can't make it yet, then don't hold back the iMacs. iBooks would be the only ones that would make sense to keep as G4 until the PowerBooks had G5s. The eMac could stay G4 using the faster ones.
However, the idea that the iMac needs some sort of detachable display is a bad one. One reason is to be able to "reuse" the display when the computer becomes obsolete because that expensive 17 or 20 incher would otherwise go to waste. But by the time that comes to pass, a 17 or 20 inch display will be much cheaper, and you won't care about reusing the old one. Besides, what are you going to attach it to? A powermac? Newer iMac with a very different design? You'd still need a base to hold it. The only practical solution there is to have a monitor in port to use the whole base+monitor as just a monitor. Having an iMac with a detachable screen is not good because, that screen would have a lot of bulk with the addition of a battery, WiFi, touch screen layer, maybe hard drive, etc. When docked on the arm, it would be bulky and ugly. The other thing is that it would cost much more than the now overpriced iMacs. People complain about the price as it is. Clearly, this tablet/remote screen role is better suited to a separate computer, and Apple would get to sell you two machines. You would have two usable machines (also think about needing to use the computer and having to track down where the screen is) for probably not much more money in the end. Now, that said, I think there most definitely is a market for an iBook with a form factor of the twist and folding screen to play the tablet role. Not just a PowerBook with this feature. As a consumer, I'd have an iMac as primary, with a separate iBook/tablet to do light work via WiFi mostly in tablet mode surfing with a stylus or my fingertip. When I get creative, I'd flip the keyboard into action. It would be nice if my login from the desktop could be used on the tablet so my mail, bookmarks, etc. are there and sync back. An interesting idea might be an Airport/tablet combo where the base station had a dock slot for the tablet that could be used to prop it up as a monitor while it connected to the wireless keyboard and mouse next to it.
I do think a consumer headless Mac is a good idea. I think it needs to have the specs of at least the low end iMac, with one AE slot, one PCI slot and a replacable video card in an AGP slot. It should have a built-in VGA port or come with the adapter for switchers with PC monitors. It should have USB 2 with two ports on the front and a lot more than three ports total. It would be very good to also have a BTO option of at least one 3rd party two button mouse with scroll wheel. The case should be nice simple box with an integrated carry handle designed to be sturdy with a footprint to function as a stand for switcher's CRT screens this will be used with. Don't restrict the BTO options - let them get a superdrive and built in Bluetooth with a smoking video card and monster hard drive. Basic unit should start at no more than $699.