Why is it the longest ever? Because we have the internet and social media. Our attention spans are less than half of what they were 10 years ago. So, even if the actual amount of time is the same or similar, it seems like forever. But, that's why i think this new generation will only last 4-5 years max. It will be hard to compete against the blazingly fast increases in power that tablets and smartphones are currently going through. Seeing as how the new consoles are technically out of date already before they launch, this problem only looms closer. M$ and Sony could launch new consoles again in 3 years if they made them completely backwords compatible, but it would segment them too much. We will probably see the same thing as last generation, incremental upgrades to hard drives/wifi/2d or 3d and dashboard/OS software that increase the capabilities without excluding early system buyers.

What if the 8th gen becomes longer 2012-2022?

Glad someobody already said so, here.

Impossible, although for the sake of the industry that would be optimal as the rising cost of development of major titles has gotten far too bloated. I wouldn't be surprised if by 2020, you'd see retail games as a limited edition luxury only the major publishers are able to do 1-4 times a year and everything else is digital due to the Indie developer becoming the main output for the major of releases.

This.. was so far off topic im not even sure you are in the right thread.

If it starts/ends with the first next gen console to come out then this gen ended in 2012 with the Wii U.  7 years.

Right, but just because one region gets things late, it's still the same amount of time passed.  November 2005 - November 2013 for Xbox 360 is by far the longest console life-span ever.  PS3 was November 2006 - November 2013.  Very long, but not as long as 360.  Wii was November 2006 - November 2012.   Relatively standard for a console life-cycle.

Because most consoles have 5-6 year cycles, 360 is 8, PS3 is 7

Xbox came out in 2005. It is 2013 now. 8 years. And the ps3 2006. 7 years. The wii is the only one that took a regular time.

I think those are Europe dates. For us here in the North America it has been longer.