If thinks keep going like this.... then 2019 will be like :
I agree on PS4 and XBO, but I think Switch is a bit low.
The console had quite a few notable releases during the first half of 2018, and yet it's getting beaten each week by some 50k margin (give or take) in sales. However, the second half was pretty barren until PLG and SSBU late last year.
This year is the other way around with Summer and Fall stoked with big releases, both from Nintendo and 3rd party publishers. Which tells me that the gap in weekly sales will grow starting with Mario Maker 2. The current trend alone already says more something like 20M, so I expect this year to break that barrier.
The Nintendo eShop rating Thread: http://gamrconnect.vgchartz.com/thread.php?id=237454