It probably will overtake the xbox, but even if it does by a margin, I would still consider the PS3 the looser of this gen (sales wise). Why? While selling a couple more console will give Sony a nice chunk of change in their pockets, it doesn't remotely cover the extra money MS made with software sales during all that time in which they had a bigger market share. This gen will be long over by the time Sony would have truly equalled MS.
Anyway, that's just the money perspective. I still prefer the Sony exclusives over the MS and Nintendo ones.
edit: typo