No offense, but you're not making any sense. The current generation has not lasted longer than previous generations, and pretty much anyone in pre-algebra could plot you a graph that would show "we can expect the PS4 and XBox 720 by 2013 at the latest."
PS1 - 1994
PS2 - 2000
PS3 - 2006
The average works out roughly the same for Nintendo, and since Microsoft only has two data points it's not really worth including them.