Hmmm, are they counting "shipped" copies among the "sold" copies. There are piles of the game in countries like Japan sitting on shelves, and being given away with other purchases. Something about that announcement of "4 million" in sales doesnt add up. There have been no actual sales numbers released, as far as i can tell.
All that said, whatever it has sold so far, double it.....i think that will be what it ends up selling. Itll go on sale and then be listed in every Playstation Store sale for a year, and all the people who wait to buy games for the price to decrease will start buying it. Itll do fine. Sony doesnt let their properties fall out of the spotlight until they have reached their sales potential.
It have broke records in all places that released notes. Sony sure is using mostly shipped, but they also have digital sales (which amount to more than 50% of sales nowadays), they have access to everyone that installed or obtained a trophy, most of what is shipped on day one comes from pre-orders, etc.
So unless you have credible source to challenge 4 millions, which would prove Sony is lying on a statement that would be a fraud on USA law due to being publically traded company, then you'lll have to accept it sold 4M on the first weekend, which aligns with the increase of sales records the big hitters of Sony have been achieving since UC4 with each exclusive beating the previous.