6 months ago October NPD looked like an easy win for the XBOX1, but things seem to be different now. So ere are some reasons why the Ps4 could eventually win Octobers NPD 

1- TGS: 

TGS convinced a lot more poeple (than we think) about the near future of the ps4 ( I actually bought the ps4 with the hype of the games announced during the Playstation experience last december.)

2-October line up

Some may considere them as not system sellers but games like UC NDC, DQ Heroes, Deasgaya 5, Tales of zistiria ...... will help the ps4 to keep the momentum 

3- BIGGEST REASON:

What happened with WiiU big games might happened with hallo 5. We know that eventhough the WiiU big games sold pretty well(ratio Software/hardware) they didn't generated crazy HW sales like some expected, due to the fact that the fan already bought a WIIU. So H:MCC as been released last here during the holiday moving lot of HW and I think from that perspective that lot of Halo fans already own an XBOX1.

4- COD BOIII(ps4 exclusive content and tournement...) VS Hallo 5:

this might be a small reason but I would considere it as an argument

5-(EDIT) Paris game week with possible price drop anouncement

(Update) Some PS4 Deals are happening in different  stores showing signs of an upcoming price cut, earlier than PGW

Then again Im not saiying that the ps4 will win but don't be surprise if it does

it wont. halo 5 will win it easily for xb1

I don't know. XBone will win in NA, sure, but is Halo big enough to push the system against the PS4 in Europe? With Japan ignoring the XBox brand, and european XBone sales not being that great (at least compared with regular PS4 numbers there), will the XBone sell enough systems to close and surpass the gap? I think the PS4 will take the lead, even if it's just by a couple hundred units.

This is what I thouigh few months ago but the "easy win" isnt valid anymore IMO

Lol I was just like you OP, everything looked set in stone for Xbox One to win October NPD, but now looking at the trend in amazon best seller (which so far have been right predicting the winner), I am having some doubt. I still think Xbox One should win, but I would not be surprise if PS4 ended up winning.

I don't wanna be that guy, but unless we are talking Globally in the US, NPD only concerns NA.

While I do want games like Disgaea 5, Drgaon Quest Heroes, and the Uncharted Collection help Sony make it a competitive month, one cannot argue with Halo's success. It is going to quite difficult for Sony to win October since Microsoft is expected to go full force in advertising and marketing. I will say this; I personally wouldn't be surprised if Sony focus is more geared toward November by mid to late month for the big holiday push.

Think the Xbox takes it, with the PS4 not that far behinde.

Apologies for being off-topic, but would you be so polite as to explain where this term originated from Henry-San? I have seen this before and understand its meaning. Just not sure as to how it came to be. Much appreciated in advance!

Nope. Halo isn't big as it used to be in past. But still Halo 5 will pull over Xbox One.