You’re trying to justify a market strategy based on unsubstantiated rumours which are likely to be untrue.
While it is possible that Microsoft/Sony could release a system after Nintendo with no negative impact, we've seen similar actions repeatedly cause significant harm to competitors within this market. To understand why this is so risky consider the following hypothetical scenario ...
Suppose Nintendo releases a system in 2012 that has a key innovation that people find remarkably desirable at a price that people believe is reasonable; on top of this innovation, the system also has a significant advancement in processing power and features. The system sells quickly and third party publishers soon decide that they need to support the system well (especially in the launch period of Sony and Microsoft’s consoles) to be profitable; and the vast majority of games are designed around Nintendo’s system, potentially with some enhancements for Sony and Microsoft’s eventual consoles.
Two years later, Sony and Microsoft release their own systems that launch at a higher price and lack the key innovation provided by Nintendo (because they’ve been mocking it since it was released as ‘gimmicky ’); while these systems have more processing power and features most consumers find these to be a minimal advantage over what Nintendo is already providing. This gives Nintendo a massive price advantage after their price cut, a massive library advantage because they hit the market first, and they’re still getting the vast majority of the same games released to their system and (while there are some enhancements) the other systems don’t get any significant advantage from these games because they were designed around Nintendo’s system.
This is not a certain outcome, but this is the desired outcome of the company that uses the first mover strategy. The whole point of releasing first is that you intend to offer enough of an improvement over the previous generation to get people to adopt your system, while also being able to defend against systems released in the future by positioning your system in a way that your competition can’t offer a significant improvement without taking on a significant disadvantage (like a higher price). In raw processing power at an affordable price I believe we hit this point already, as it is unlikely that next year's $600 graphics card will really be that much better for most gamers than a $150 graphics card that is available today; obviously, I mean when you're comparing these cards based on relative improvement over the HD consoles.