sc94597 on 16 June 2017
I'd say a few 100k over its lifetime, more than a few if they bundle it at a good price. I think Dragon Quest XI will have a bigger immediate impact on the PS4's Japanese sales to be honest, but probably not as much of an impact in the long term.
The game will probably sell about 1-1.25 million lifetime in Japan (with price drops), similar to Monster Hunter Tri, but it will sell more PS4s than Tri did Wiis because the Wii already had 10 million sales in Japan when Tri released.
