We will see. Talking about "% down YOY" after a week and half in 2019 can't represent the whole picture in 2019. Let's wait and see. Switch was surfing the wave of the most casual month of all, which is December, let's see what happens when figures stabilize, and it's already happening. NS week ending 22 Dec 2018 : 1,546K(PS4 789K) week ending 29 Dec 2018 : 848K(PS4 502K), week ending 5 Jan 2019 : 449K(PS4 356K), week ending 12 Jan 2019 : 252K(PS4 221K); the trend of Switch is selling 55% , 53% , 56% the amount of the previous week in the above mentioned weeks, while PS4 64%, 71%, , 62%. Switch is slowing down like a rocket, more than PS4, as it has got the maximum boost from Dec, the "month of casual gamers". I'm more than sure that right now PS4 is on top worldwide, and it will be for many many weeks up to Nov 2019. It will be a bit down YOY ? It doesn't matter if PS4 will be slighty down YOY in 2019, it does matter that PS4 will make other 17M in 2019, keeping sales healthy and steady, after 6 years from release, which is a miracle if you ask me.
Switch was coming off a December this time last year too, yet as of these numbers it is up 25% YOY.
Bet with Liquidlaser: I say PS5 and Xbox Series will sell more than 56 million combined by the end of 2023.