I don't think all 3 consoles will drop in the same year. The way the Wii is trending year to year, 2012 is the best bet for the Wii 2 to be released unless Nintendo puts out a killer app that sell along the lines of Wii Fit, Wii Play and New Super Mario Bros. Wii in 2011. Sadly, I don't think Zelda Skyward Sword will be that app.
My gut tells me a 2012 holiday release for the Wii 2 followed 8 months to a year later by the NeXtbox and PS4 within a couple months span of each other.
History has shown with the Dreamcast (Released in 1998; PS1 released in 1994; N64 released in 1996) and Nintendo 64 (Released in 1996; PS1 was released in 1994) that if a console launches 18 months or later after their competition in the latest generation, they will never be the top selling console of the latest generation.
The sole exception to this rule is the Super Nintendo which released in NA in 1991, 2 years after the Sega Genesis was released in NA in 1989. I don't want to say much further as the SNES vs. Genesis debate is a long and convoluted one.
Wii 2 - Holidays 2012
NeXtBox - Late Summer/Early Holidays 2013
PS4 - Holidays 2013/Early 2014