It will be very interesting to see how well the next set of consoles sell.
Everyone is on the WiiU -- and rightly so given its post-holiday sales. But people ignore that it started out BETTER than the PS3 and Xbox 360.
Given that the graphical jump is not as huge (or not as noticeable), given that the games will be available on the previous systems, given that there will not be (or be limited) backward compatibility, and given that there may be issues games not on the console to which they are first played (this includes used games, rentals, and gaming-with/at-friends), it might be that adoption of the PS4 and NextBox are slower than expected.
The WiiU has had not of the above issues* and its adoption has been slower than expected. (*It has had a game drought and a lack of third-party support.). Plus, the economy is many countries is somewhat shaky right now, which means people may not want to so quickly spend money on something of limited added value.
More information is needed to know these things with any certainty.
Mike from Morgantown