Where did I say I was talking about *average*? I distinctly remember saying that my calculations applied to what is possible at what time, not when it becomes average.
What the hell does a console maker care about average? He's looking to build something that is technically cutting edge, feasible and not priced beyond reasoning (but still prepared to eat a lot of the initial cost to encourage sales).
The only place console makers tend to care about "cutting edge" is graphics. Everything else is designed to be as cheap as possible without limiting the graphics too much. Neither the XBox 360 or the PS3 were cutting edge when they launched. Innovative, yes. Overpowered compared to the current tech? No. 360 in 2005 and PS3 in 2006 both only had 512MB total ram, at a time when people's
graphics cards were starting to have that much memory, never mind the main RAM. In order CPUs, half wide buses, low CPU cache sizes. These don't scream "cutting edge". Multiple cores were ahead of the game, but even those are more because it saves in development cost and there was not much gain in clock speed at the time.
The reason the consoles kept pace well is simply due to resource allocation. If you open task manager, you'll often see hundreds of processes on your windows (or Linux or Mac for that matter) box. The XBox and PS3 tend to have basically one. When these machines are running your game, it's
all they're running. There's no memory manager or paging, there's no exception handling, there's no process switching overhead. It's like if
every app on your PC had 95% CPU, 480MB dedicated memory (and no paging) and almost all the GPU.
Combine that with developers coding to well-defined, static hardware, and that's why the consoles still look pretty good.
For next gen, we want more texture space, more CPU (for better AI), and a beefier GPU to handle all that extra data. I'd be extremely surprised if any of the next gen consoles goes over 4GB combined RAM, simply because that's about where graphics cards are now, it allows a 32 bit flat memory model, and it's at 8x the previous generation, which was 8x their previous generation. Even 2GB might be possible, since there's diminishing returns at a certain point with texture resolutions.