It doesn't have to sell double its sales for the game to sell "well" on next gen systems.
A game that had 10% as many sales as GTA V would be in the top 150 games for the Xbox 360 and top 100 games for the PlayStation 3.
A lot of people will buy the game again. Others will buy it for the first time. The PlayStation 4 and Xbox One sales will add up to millions of units sold, which means tens of millions of profit. I think there's plenty of room there to make the porting worthwhile.







