This game looks good, the graphics look next-gen though they won't blow your socks off. The issue with the lifetime sales at this point is that they are entirely tied to the installed base of the PS3 by the time this game comes out. If when Tekken 6 is launched the PS3 has picked up steam, then I can see this game selling into the 2 million range; as Tekken 4(PS2, 2002) sold around 3.3 million, Tekken 5 (PS2, 2005) sold around 1.32 million and Tekken Tag Tournament sold around 3.9 million (PS2, 2000).
I can see this game selling more than Tekken 5 since this will be the first new Tekken for the system, if you notice Tekken Tag Tournament is the first Tekken for the PS2 and it appropriately has the largest sales. Anticipating a larger install base of the PS3 would probably give this game at least half a million sales in Japan and another million in the States, possibly. Overall I think it will sell in the 2 million range over its lifetime.
5
I can see this game selling more than Tekken 5 since this will be the first new Tekken for the system, if you notice Tekken Tag Tournament is the first Tekken for the PS2 and it appropriately has the largest sales. Anticipating a larger install base of the PS3 would probably give this game at least half a million sales in Japan and another million in the States, possibly. Overall I think it will sell in the 2 million range over its lifetime.
Sources:
http://vgchartz.com/worldtotals.php