Yeah. double, and even more.
Assassin's Creed Unity will sell much less of one normale Assassin's Creed.
The people are tired of usual IP. They want NEW game.
And Watch_Dogs it is.
Watch_Dogs will sell more of 12 million lifetime.
4 million on PS4
2 million on XBOX ONE
2,5 million on PS3
1,5 million on XBOX 360
800,000 on Wii U
500,000 on PC retail, and between 2-2,5 million with digital
Sommary: between 12 and 14 million
Assassin's Creed Unity will sell less of 5 million.
2,5 million on PS4
1 million on XBOX ONE
400,000 on PC retail, between 1-1,5 million with digital.
Sommary: between 4 and 5 million
Yes, i think even little less of triple... this is my prediction.
In the best scenario, for me, Assassin's Creed Unity will sell 1/2 of Watch_Dogs.
Maybe Assassin's Creed Unity have sould sell even 8-9 million if coming out on old gen and WiiU... but only on PS4, XOne, and PC, no.
This is my prediction, Watch_Dogs is the new Assassin's Creed, I may be wrong, but for now this is my prediction. 
