Highly unlikely because it would have to have massive legs in the west to close the gap.
Then FFXIII still has a platinum edition, international edition in Japan.
International editions in Japan took FFX from 2.2 Million (original saleS) to 2.9 Million
They took FFX-2 from 1.9 Million (where FFXIII is near now) to 2.3 Million
FFXII's international edition in comparison sold like 150K.
As each 100K is added it gets harder for DQIX to catch up.
By the end of the gen it is likely FFXIII will be around 6.5 Million after platinum editions and so on, I don't see DQIX getting much over 5.3 Million in the long run.
So its unlikely and I don't think it deserves to outsell it either.
A better question would be, will Dragon Quest IX outsell Final Fantasy IX.
