Enough data and evidence is in (as if you needed it before) that suggests PS4 will runaway with this generation, to what degree depends on how hard Microsoft fight with Xbox One, but whatever they do it's not going to be enough to take the lead.
Gen 5 - PS1 - WINNER!
Gen 6 - PS2 - WINNER!
Gen 7 - Wii - LOSER
Gen 8 - PS4 - WINNER!
So this comes down to if PS3 can overtake the Wii, the gap stands at about 19m~ having sold 9m+ this year (when holidays finish).
Can Sony do 4 in a row?
Also in the somewhat unlikely event Xbox 360 overtook Wii, the last 3 (6, 7 and current) generations could look like this
Sony > MS > Nintendo.