Back on the late Wii days the Nintendo console was, indeed, proportionally stronger on its holiday period than its competitors. However, last year the Switch was outsold by the PS4 in November-December. So, while some are expecting a repeat of the former, other are expecting the later. It's not unreasonable.

Of course it isn't certain, but I would say it is more probable than not. If I recall correctly, The Europe/RoTW sales for this year are doing better than last year, so assuming Smash has the same/similar impact that Odyssey had on USA/Japan, there's a less of a chance giving the ps4 at huge of a lead. 

Last year Switch had some stock problems, didnt had any deals and Pokemon+Smash Bros are defintly stronger than Mario Odyysey+Xenoblade 2.

Though on the other hand a systems "first christmas" will surely bring a boost to some extent, i.e kids who want a switch when they hear about it, and there parents telling them to wait for it as a Christmas present.

There's too many variables.

I think Switch will outsell PS4 in nov+dec, but by around 1m-1.5m, not quite enough to claw back the gap.

How is it more probable that Switch will win July, August? September through December is possible in the US, but worldwide might be another matter. It might win November and December world wide but it would have to close a pretty significant gap to come out on top overall in 2018.

At their current rates, the PS4 will reach 80 million in the first half of June, the Switch will reach 20 million around mid-end August. This is significant because PS4 will have sold 6.4 million units in 5.5 months while Switch will have sold 6.8 million units in 7.5 months. By the time Switch reaches 20 million the PS4 could have sold another 3 million or so bringing it to 9.5 million sales for the year in the same time it took Switch to sell 6.8 million.

Unless Switch somehow starts beating PS4 week for week mid year, how will it close that gap? It's widening 40-50k every week. That will all add up.

I think this year we will have a technical tie, 18 million each.
Next year, definitely switch be ahead.

Yep 2018 should be the last year PS4 have a chance of outselling Switch unless something really unexpected happens.

Could be, I think it will be very close. Hopefully down to the exact number so neither side can claim victory.

Console in its PEAK + incredible deals vs a new console couple of months old facing stock issues and with no deal or even bundles. A console in launch period isnt going to sell 20 million consoles lmao. It did like what almost 17 million vs 14 for the ps4.

Y'all need to realise first year =/= sales for life. Switch faced a drought (which is normal after first months of launch) and nintendo literally didnt announce anything for the future during this period so the hype naturally went down. The console still stayed around 200k a week without big announcements or big games for months. 

Switch is finally getting some support in Japan and sales their will explode with the upcoming games. Switch is also growing fast in Europe, even in the UK it is doing really well compare to a couple of months back and that's without any big titles... DKC did that so imagine when pokemon and smash are coming. Switch still have some places to release in RoW like China and Arena of Valor is entering beta soon if thats any indication of a release there soon.

Not saying ps4 can't win the year, but judging the Switch on its first year (which was one of the best of all time for sale numbers) which clearly had stock issues and no deals/bundle and looking at numbers from the drought period when the second half is packed of game is so dumb.

Ps4 didn't win by that much and had GoW, MHW, SotC etc and is entering a somewhat drought in the next months.