Overall Sony had a very good year, and also a solid holiday season. But. The December results in the US indicate that this year's peak, especially the outstanding November performance, was clearly driven by discounts of the baseline SKU. I think going back to $299 for the first two weeks in December (after that $199 BF week discount) was not only a move to crossfinance that $199 discount but also some kind of experimental move to test the attractiveness of the Slim at $299 in a timeframe where people usually buy gaming consoles. And apparently the $249 a week before Christmas wasn't nearly good enough to make up for that two weeks.
If so, that experimental ballon surely was a true reality shock for Sony. I mean, it was clear from the beginning that there would be a major gap, but probably not like this. The truth is that PS4 needs severe discounts to move a serious amount of consoles in 2018 an ongoing. Neither MS nor Sony can "afford" selling their baseline consoles for $299 throughout the year. And I am talking MSRP here.
Thing is, the people you attract with those discounts are the (super) price sensitive ones. So they are the ones who also tend to buy used instead of new games (which also means they don't buy digital that much) and avoid costly online subscriptions (at least I expect that the PS+ attach rate is significantly lower compared to those who bought an OG PS4 or a Pro for $399).
My conclusion is that the results indicate that Sony needs to introduce a PS4 successor which attracts the price insensitive consumer segments rather sooner than later, as in 2019 or 2020 at the very, very latest.