In my opinion, I would expect that any consoles released in 2010 would have to be green lit by the end of 2008, any consoles released in 2011would have to be green lit by the end of 2009, and consoles released in 2012 would have to be green lit by the end of 2010.
I see no reason why Nintendo or Sony would release another console in the immediate future, and they're both (probably) waiting until someone else makes a move (or they have saturated the market) before they release a new system.
Microsoft, on the other hand, is in an awkward position in that the XBox 360 is struggling even though it is the least expensive system with (in some ways) the best software line-up. The XBox 360 is simply getting lost in the mix and, although it is unlikely that software support will drop away like it has in previous generations, it will be difficult to increase demand for the system when exclusive third party support for it will become rarer and rarer. In other words, I wouldn't be surprised to see Microsoft release a new system in 2010 or the first half or 2011 which would make them the first mover again.
