Xbox One: 2.8 million
Xbox Scorpio: 1.3 million
Switch: 5.4 million
PS4 6.5 million

PS4 - 5.0 millions

XOne - 5.1 millions

Switch - 5.3 millions (assuming there is no undershippment throught the year)

3DS - 550K

Edit:Thinking better, all these numbers really depend on what the Switch ends up shaping.I will leave this numbers here, but depending on what happens in the 12th, ill make them higher/lower.

Edit 2nd

PS4      6m

XB1      3.8m

Switch  3.5m

PS4 > XBO > Switch > 3ds > WiiU

2017: (my guess)

PS4 ~6m
XB1 ~5m
Switch ~5m

Im expecting : PS4 > switch > XB1.

XB1 and Switch are gonna be close, PS4 a tiny bit above either.

shouldn't the OP be updated now that we have numbers for december 2016?

PS4 [5M]
lots of titles with sony marketing so I am expecting a lot of bundles this year and a price drop. And unless something changes, we at least know of destiny 2, SW;BF2, ME:A marketing deals, and sony first party bringing horizon, detroit, Gran Turismo....etc. There could very well be as many as 5 different PS4 bundles this year with some even having more than one game.

XB1 [4.6M]
scorpio isn't going to do what some think it will do for xbox, and unless halo 6 comes this year or they have some yet unannounced marketing deal with either ME, BF, Destiny 2 or COD or RDR2( I am secretly expecting this game to be MS great marketing coup of 2017) MS has got a very weak software lineup for 2017

NS [3.2-5.2M]
Big range I know, but a lot is riding on which kinda consumer primarily buys the switch. If it turns out being the hot holiday item based on whatever word of mouth it generates through the course of the year and sells as both a great console and handheld, then it should do 5M+ easy barring supply issues. If its only picked up by the Nintendo faithful then I expect no more than 3M.

3DS [2.0M]
i expect NS to cannibalize 3DS sales. In truth, there is no reason the 3DS should exist now that the NS is going to be on the market. The switch does what the wiiU and the 3DS did but better.

WiiU [300k]
I just couldn't put zero. But I can't imagine why anyone would buy a wiiU. The market will also be flooded with used wiiUs.

Edit 3rd.

PS4       6m

Switch  5m

Xb1       4m

You cant keep editing, thats not fair! lol