Microsoft for the lulz.

Virtually tied (within 1m of each other).

What can really help the Switch is when people see them in public. Owners playing them on the go can really increase interest to those unaware of the system. Ash Paulsen from GameXplain mentioned having a personal experience when a kid noticed his Switch while in an airport. Not saying that's gonna happen right away or be effective, but the potential is there. We're seeing that on social media with people playing the Switch in conventions, at school on break, at cafes, etc. it's a fascinating device since it can play console games like BOTW and Mario Kart 8 Deluxe, which is something even the Vita can't claim.

if we see a holiday small price drop or even just a good bundle the switch could do extremely well.
The Xbox Scorpio is also more likely to impact ps4 sales then switch sales, think about it.

Either way it will be pretty close but Sony is still the fav to outsell the 3ds+switch because of the known lineups for the end of the year and also the big AAA blockbusters from third party not being released on switch (as far as we know)

They'll just close the gap later then. Nintendo is still capable of releasing a console worse than Wii U that will give them negative sales.

If that happened, it'd either mean that the Switch had a really good year of the PS4 declined significantly, wouldn't it? Or that the New 2DS XL was a huge success!

my guesses:
PS4 18
switch 13M
3ds 5M

tie

10 million is an extremely conservative projection by Nintendo so, yes, hardware units wise they probably will be at #1 this year. That said- revenue wise they'd probably need to sell close to as many Switch's as PS4's to match as the 3DS (and particularly the new 2DS XL at $150) sell for considerably less. 

will be interesting to see who ends up at #1 this year mainly because the Switch looks strong and then NIntendo has a much larger boost from the 3DS than Sony with the Vita 

Highly doubt it. I think both are going to slightly outdo their predictions, both by ~2M, so it'll still be a 4M gap. Nintendo is less of a guarantee, though, as it'll depend on how it does in a couple of months past the launch window. So far, it's doing pretty darn good.

PS4, on the other hand is almost guaranteed to at least match this past fiscal year. We have some big launches this year, which Sony has exclusive advertising and bundling rights to. We'll also see a cut to $199 for the PS4, the first this gen. That should give it w nice boost this holiday season. The Pro will also see a $50-$100 cut this year, which should help it contribute more to those final numbers.

Nintendo definitely have solid chance with Switch and 3DS.