This endless delusional optimism from the most extreme PS3 fans is getting old ...
The higher development costs and lower hardware sales of the PS3 is already traslating into third party publishers taking smaller and smaller risks on the PS3. This low risk mentality will translate into fewer and fewer exclusive games, and games that are developed for the PS3 will be heavily focused in genres that already have several games that are million sellers. What this means is the PS3 will seem like a better system to the kind of people who own a PS3 already, and a much worse system to people who have been unimpressed so far.
In the previous generation the XBox and Gamecube started to have difficulty attracting new customers when they reached 20 Million in sales because they lacked the broad appeal to sell to the typical gamer audience. Being that the market has grown and the difference between the Wii and the HD consoles is more dramatic the HD consoles should be able to get a little further than the XBox and Gamecube did; but by the time each of the HD consoles starts to approach 40 Million in sales, everyone who really cares about FPS, Racing and Sports games will already own a HD console.
Finally, next year we will start to see inexpensive laptops ($500 to $750) which are noticeably more powerful gaming systems than the HD consoles, and even fairly modest gaming PCs will start to devistate the HD consoles. At this point in the generation there is a resurgence in PC gaming as most graphics whores return to their "Home" in the PC gaming world, and western developers start to return focus to suiting their needs.