Kongfucius on 15 November 2013
I think UC4 or whatever it ends up being called will show a slight decline from UC3, because some people will have had enough of the series after 3 main games, but this will be cancelled out in part by the increased success of the PS4 compared to the PS3 (bit of an assumption there, but I'll stand by it). That said it could be very dependent on what they actually do with the game - we don't know if it's a spinoff or a true numbered sequel, or if Drake is still the main character (personally I think they should give Sully his own game set in the 60s or 70s, but that's an argument for a different thread)
