Xbox launched in Nov 2001.
Xbox 360 launched in Nov 2005.
Xbox One launched in Nov 2013.

Xbox to X360 was 4 years.
X360 to XOne was 8 years.

Microsoft could have launched an entire generation inside the 7th gen and still launched the Xbox One in Nov 2013.

Will we ever see a 4 year cycle from a console maker again?  Could Nintendo launch a new console in Nov 2016?
Or will we see 8 year cycles as the new norm? Meaning 2020 as the earliest (Nintendo?) new console?

A new Nintendo home console as early as 2014 won't happen imo, I have my eyes set on 2016, personally. That said, I think this gen will be around 5 years long, perhaps 6 for the market leader.
Also; that's crazy, I didn't realize the original xbox had such a short lifespan!

My apologies. I think I put 2004 rather than 2005 for the X360 launch.

All else still applies.

For your first question that's a no aside from Nintendo possibly releasing it's next iteration in 2016 and that's mostly to get rid of the terrible image of the WII U. As for you second question that's mostly a yes because as we start reaching the limits of moore's law the chances of performance gains start occurring less frequently over time as we have always depended on process node shrinks to boost performance by a significant factor.

I see this generation riding out for ATLEAST 10 years!

My question then is....Is that due to the reliance on node shrinkage for performance increases or simply due to the costs involed with software development that require long generations to ammortize costs across multiple products?

I think Nintendo will switch within 4-5 years since the launch of wiiU, and X1 and ps4 will be 6-7 years

It's a little bit of both I'd say.  

As AAA development costs keep skyrocketing there is a need to create new tools such as engines for next generation platforms and libraries for each of those platforms and all of these are expensive so you could say that one part of it is to repay back the initial expense. The other reasons being that process shrinks don't occur very frequently as we reach the limits of moore's laws and therefore console manufacturers don't see it necessary to release new platforms in as little as 5 years as performance will only increase by a factor of 3 at most. 

Good post.  But where does console maker intention and software developer demand meet?  Is a new gen console solely at the discretion of a the platform maker or are the demands of software providers of equal importance?  And if so, could their demands instigate a new generation before a console maker would have liked by themselves?

Wii U launched in 2012 so a 4 year life would put the new system in 2016, not 2014. And sure, I think it's possible.

*blarg*  Damn typo.   2016 indeed.  I was thining "4" years...so "2014" got typed knowing full and well I meant 2016 in my head.