I would think that around the 2017 mark would be a good time for the consoles to go 3d with 120hz tv's being widely available on the market. They are just making their way back now and you can get that nice True3D at home with the right lcd/graphics card.
While the 360 broke the first three years of its life, They now have (i think) reliable boards and with Sony springing ahead with the Slim, it may just be a battle of design over the next few years. Do we really think though that new systems wont peak out at the end of 2011?
2011 marks the PS3 and Wii's 5th birthday and 360's 6th. The 360 may actually release something first just to be first to market again while Sony and Nintendo begin to fight it out. Sony did have a price problem, but it was one they created themselves. "We want people to need to save up for it" from e3 back in the day. So at least they got the BlueRay going, and by the time 2011/2012 comes around Digital Distro is supposed to be spiking making the tech a bit worthless. So they can cut out the price of the drive and all the console makers (read MS and Sony in this one) except for Nintendo will be forging ahead grabbing all the latest DD rights and spreading much Propaganda to sell themselves as the ultimate box that does everything without DISC! While Nintendo will show up to the table, clinging onto the older formats with a more robust DD channel downloads and what not. (but anyone else worried that VC and WiiWare titles wont go to the next platform?). Companies like Capcom will forge ahead with MS and Sony with just a couple releases available to the Nintendo Audience and the world will continue and Insanelord will still be a graphics whore...
hehehe... you told us to call you that.. that makes 2 for me!
edit::
Oh yeah, as a victim of economy and companies shutting down, I don't see peoples financial clearing up by that time and I am sure the parent companies agree. With the release of the wands and natal coming out one day, those will most likely take the place of system launches and give the console makers another 3 years of life. In the computer market, but the biggest thing to happen on the GRFX side of things is the 3D again. Other than that, I haven't seen any trends that would point to something scaling down for consoles any time soon. So, my prediction is that the systems out on market are going to stretch out till 2015, where Nintendo will launch 1 or possibly 2 years earlier than the rest ( and carve out a better release schedule from the competitors)as it will be most definitely time for that box to be retired. Of course, there is always the Phantom...