Given X360 had at least a year of the market to itself as a head start and significantly better pricing the fact that PS3 overtook 360 at all is quite an achievement.The PS3 didn't outsell 360 by some margin, in fact it was only this year I think that it overtook the 360 sales.
In any case, I think Sony will romp the early sales for PS4 at 2:1 but I expect XO to catch up a year or so later as more casual gamers/people interested in the single box under the TV in the living room stuff has the opportunity to prove itself attractive outside the dedicated console gamers market.
Either way I hope both do well, it can only be good for gamers all round and as a PC gamer as well I'm hoping XO using DirectX will prove a boost for titles coming to PC.