Why would PS4 want to do Wii numbers all gen? That means they'd crawl to 100M, instead of easily passing it like the PS2, which it's currently otpacing.
And let's just ignore all the Xbox fans' predictions and threads about how the XBO was going to actually compete with the PS4 WW, possibly beat it. Which started up again when XBO did well the following Xmas after launch. Now, it's only competing in the US when it's $70-$100 cheaper than the PS4.
There were a lot of preditions. Even I couldn't belive some crazy ones like the WiiU failing to break the 20mi mark.
There were people claiming the PS4 would do Wii numbers (30mi per year) without winding down, going up to 250mi total or more.
You can not just dismiss the Xbox performance for it being cheaper. One of the major reasons for the PS4's advantage was precisely costing $ 100 less. I hope you will not disregard Microsoft's engineering effort with the "Xbox One S", when finally equaled to the PS4 in size (or at least come close), if it start beating the PS4 in the USA, at the same price level.
On the off-topic of PS2 numbers and claims.
You can not exactly align the two launche windows. The PS2 had a slow start, but by 2002-2003 it was doing 20 million per year and kept its pace for 3 more years. And survived long into the PS3 era.
We all know that this is impossible now and even Sony want faster generation refresh.
Of course I can " dismiss" it. The XBO has been $70-$100 cheaper, with a bunch of games, the entire month. Yet, if the 7K-10K thing holds up, it basically tied the PS4.
But sorry, the PS4's success has much more to it than just price. They came out with the better HW. Had the better policies. Had the bigger gaming brand. Had larger 3rd party and indie support. And it didn't take long for XBO to match its price, yet that changed nothing about its situation. Nor did being just $50 cheaper. Price has little to do with it.
You also can't look at the 1st month of the Slim's sales. I can guarantee that once the Slim boost is over, and both the consoles are $299, the PS4 will continue to easily outsell the XBO. In the US, of course. It's already doing that easily WW.
And the slow start excuse didn't stop Xbox fans from aligning the 360 and XBO's launch to brag about it outpacing the 360. Even though it's quite obvious the XBO will maybe pull half the sales of the 360.