Apple is due for a new Mac design. While the current desktop Macs are functional, they don't have the character of the old ones (think of the iMac G4, for example, versus the iMacs made since 2004--they have looked like glorified monitors for seven years now). The designs are also dated--aside from the aluminum revision, the iMac hasn't changed much since 2004; the Mac Pro looks nearly identical to the "cheese grater" Power Mac G5, which came out eight years ago. (Compare that to the G3/G4 era, when the design changed every year).
I wouldn't be surprised if the iMac gets a smaller frame, a different base (I still miss the swivel ability of the G4), or comes in a larger "home theater" size with a built-in Apple TV.
I think they're content with the current line of laptops. I agree about the great emphasis on the MacBook Air. I think they have themselves another "Mac for the Masses", much like the original iMac or (for you old-timers) the Classic. Think of how the original iMac was marketed--relatively low price, everything in one box, innovative design, suited for the web, multiple trim lines/equipment options to meet all needs and price points. It's not that different than the MBA with the exception of the color scheme (you're stuck with aluminum, no choosing between different colors or patterns). I make the comparison to the old Mac Classic because of the 2010 Air, which used an old chip (the Classic used the 68000 six years after it was first seen in a Mac; the MBA, of course, used the Core 2 Duo four years after its Apple debut). In both cases, the old chips were used to keep the price at $1000 for the base model. Note, too, the lack of expansion in the iMac G3, MBA, and Mac Classic.
Forget about a mid-range modular desktop Mac. It simply won't happen, and my article on Mac 512 will explain why:
Home of The Mac 512 | mac512.com
Finally, you can rule out a video game console, and not just because of the failing of the Pippin. It's just not a business Apple seems to want to be a part of, and for good reason--sales are slow, the major players are entrenched, and the market is drying up a bit (I recently read video game sales were at a recent low). Sure, Apple could probably innovate in this department, perhaps a touch-type controller, but I just don't see it happening.