I unlike other posters I think the name of the game will be speed, efficiency, security, and cost. The goal will be quick development cycles with the bare minimum of cost. This offers the quicker return in investment. It is a simple enough strategy build the game for the best platform as quickly, and as efficiently as possible. Which keeps the upfront costs down. This allows for a faster return on investment, and alleviates the dangers of liquidity in a soft borrowing market.
This basically consolidates risks, and makes them far more manageable. This also gives developers the potential of test marketing. Rather then casting a wide net. The first platform lets them measure the success of a product. Then if it is sufficiently successful they have two options. They can petition the manufacturer to buy exclusivity, or they can do quick and dirty ports in less then six months. The result is they take fewer risks. In this economy that is good business. Building for multiple platforms can be more profitable, but it can also be a financial abyss if the product fails. Better to build one game that does not pan out. Then to build six and have none of them pan out. Do that enough, and you are out of business.
Big companies can afford to take the big risk by multitasking development. Smaller companies do not have the necessary reserves. So while large companies may set their nets wide as they usually do anyway. Smaller companies are prone to become more concise, and make strategic choices.
I expect the platforms that will be hardest hit in this order PSP, PS3, DS, Wii, 360. Which basically follows the line of risk. Before anyone says why is the DS there. Well the answer is very simple competition and financial backing. That is a very competitive library, and shovel ware which is often venture capitol will see a thinning. You know as that group of investors is shy of spending money especially on butterfly farming. Ironically that idea would have flown a couple years ago. With no problem, but now investors are far more discerning. The Wii should do better for being a short term trial market. The 360 obviously has a rabid user base to fall back on.
What should be interesting is the fact that this is a buyers market, and both Microsoft and Sony do enjoy buying. With a tight market they can secure exclusives for much less, as developers try to mitigate risks. So as strange as it may sound we may see more exclusives if the players decide to put their weight towards securing titles.