I don't think Sony sticking with the PS2 and waiting an addtional 5 years to launch PS3 would have worked out any better for them. With no PS3 being available for the foreseeable future, hardcore gamers would have hopped onto the 360 platform even more quickly. The fence sitters that have no interest in the Wii, but are deciding between the PS3 and 360 would just have the 360 as there choice. Games like FFXIII and MGS4 would more and likely be 360 projects before the developers behind those games like creating games on the most technologically advanced hardware.
The non gamers and diehard Nintendo fans would still be buying the Wii in massive numbers. A large part of the market for the Wii are consumers that are turned off by the more "complex" controllers of the 360 and PS3. They wouldn't affected by Sony staying with the PS2 because they did not show interest in purchasing the system in spite of its price and games selection.
The casual gamers don't usually upgrade to new consoles until they reach a mass market pricing level. These are the consumers that are currently sticking with the PS2 anyway. They wouldn't shift over to the 360,PS3, and Wii until they are priced below the $200 level.
In essence your plan for Sony would be better in the near term, but in the long term they would be in deep trouble. Sony would be better off financially initially because they would have to absorb the R&D costs and losses associated with the manufacturing of the PS3. In the long term they'd be screwed because the would have given away the hardcore market to MS and to a lesser extent Nintendo for a market they are currently retaining anyway.
That market would start eroding away as rapidly when the 360 and Wii were both below $200. In fact when the 360 hits $200, the Wii will probably be $99 to $129. When those consumers go to pick up a new console Sony will have nothing offer them. Worse even if they scrambled to produce a new console to stop their userbase attrition, it would more and likely end up being more expensive than either the 360 or the Wii. So Sony would be living off of the same hardcore market they are trying to make a profit off now, but they wouldn't have the PS2's profits to lean for your hypothetical PS3's launch. They will have ridden the PS2 horse until it dropped dead. Can you imagine the Sony taking the types of losses they are taking currently with out the PS2's profits as a countermeasure?
