Fall 2010 will bring out Natal, Halo:Reach, and a $50 price cut/MS console revision:

-There will be one 360 model that is slimmer

-PS3 will drop the ps3's price to $250 in reaction and begin heavy Move support to counter Natal while using SOCOM4 and Resistance 3 to counter halo.  HEAVY MARKETING!

-The Wii will drop to $150 and continue to sell more than both consoles but steadily the software and outselling will diminish.

-Move will sell more if it comes out first

In 2011 Move will be used in practically every PS3 exclusive along with 3D and also in several 3rd party games.  360's will create several action games that sell ok with natal and a slew of kids/family games will sell.  Eventually both 360 and PS3 will include 250 gb HDD's standard. 

In 2012 both 360 and PS3 will lower their prices to $199 and Wii will sell for $100.  Many exclusives will be seen on all consoles and talks of next gen will become prevalent.

In 2013 Natal support will remain for only the casual crowd and 360 sales will see a very steady decrease little to no exclusives are released.  As 3D and blue-ray become mainstream PS3's will continue to sell as the main 3D blue-ray player/All-around great gaming device.  Wii will keep chugging on with great but not grand sales.

In 2014 the next XBOX will be unveilled/released.  It will have no disc support and a 1TB HDD. The 360 will sell under 85 million.

-The Wii will release its next console in 2014 but the wii will be produced until 2016 which will bring its total sales to 130 million.

-The PS4 will be released in 2018.  The PS3 will continue to receive great sales until 2020 as it will sell as the best multi-media device for a cheap price and the third party titles for the 3rd xbox will also be made for PS3 with slightly inferior graphics but much more support since it has a larger base.  The PS3 will sell a total of 125 million consoles.

Possible changes:

-A new generation of XBOX is not released and MS focuses on cheap and easy gaming PC's since it receives 3rd place twice in a row. MS decides to cut their losses.

-Natal sells big and 360 and PS3 come to a very close final of arround 100 million each (Or slightly more for 360).  The wii will sells less because of the support for natal as it is even easier to use and basically all 3 consoles sell the same amount.

-Nintendo introduces an HD version of the Wii in 2013.  It will cost $200 while the wii sells for $100.  The wii HD and normal wii will still use the same games but the wii HD will have optional install on its 250 HDD and in 720p with graphics tuned higher (Like graphics are tuned differently based on a PC).  Games on the HD will look like COD4 quality but no better.  The wii will then sell 150 million+ units as the greatest selling console of all time.

P.S. That was long but that's what I predict.  Please respond with detail in how you disagree and in what part of my prediction you disagree.