Oh, are we doing one of those "ignore the Wii" discussions? In that case, the PS3/360 battle isn't remotely comparable.
Even in its early days, the PS3 was selling about 80% as well as the 360 was -- the initial gap was fairly large, but mostly a consequence of the 360 launching a year earlier. By contrast, the Xbox One is selling about 60% as well as the PS4 is. That's a huge difference.
Right now, based on what we know, the PS4 has sold ~16M units worldwide, and the Xbox One has sold ~9.5M units worldwide.
If instead we had ~16M units for PS4 and ~13M units for Xbox One, I think a reasonable person could imagine this changing. But it's not remotely that close, and as such, it isn't reasonable to expect a change.