There's currently 43 million sellers.
+ Final Fantasy XIII
+ Assassin's Creed 2
+ Need for Speed: Shit
+ Tekken 6
+ Midnight Club: Los Angeles
That would make 48 million sellers.
Maybe:
+ Mortal Kombat vs DC Universe
+ Tomb Raider: Underworld
That would make 50 million sellers.
Pretty close but I don't think 50 million sellers will happen.