This is a tough call but I would say 150 Million with a possible 200 Million if it has an extended life and china/india/russia gaming markets have a very fast growth within it's extended life.
Playing : PC AOE, DiRT 2, Runes of Magic, Wings of Prey & Planetside 2
Wii U : Nintendoland, Super Mario U & Fifa 2013 demo
DS : Guitar Hero : On Tour
Formerly unknown as Vengi