http://gamrconnect.vgchartz.com/post.php?id=5039861
I did some maths using Ubisoft's figure about how much it cost to port games to Wii-U and Barozi's pie chart for the breakdown of a $60 game in that post.
If any of those numbers are in the ballpark of being correct, then it would only take about 50k copies sold to make the game break even. But it depends on the game more than anything else. Although Ubisoft had cited $1.2 million for their ports, I reckon that figure would be closer for something like Just Dance than it would for Assassin's Creed 3.
Either way, I suspect the more successful ports (Blops, Assasin's Creed, Batman) would have at least recouped their costs plus some profit. The lower down stuff such as Tekken and Mass Effect may be struggling, though.
