Improbable. The PS4-Switch gap has been growing all year:

As of May, the PS4 has a lead of 324k. With the Switch about flat YoY and the PS4 showing no signs of a sudden crash in sales, that gap is going to continue growing. By the end of October the PS4 could have a YTD lead of 600k or more.

Going in to November, Sony will almost certainly issue the usual big Black Friday price drops. The PS4 will sell well north of a million units, maybe 1.4M or more; last year it sold 1.58M, the third-biggest sales performance for any console in November. Meanwhile, the Switch sold something like 770k, give or take (I don't think we ever got an exact number). To even have a chance of beating the PS4 in November by enough to make up the deficit it will almost certainly accrue by October, Pokemon Let's Go is going to have to be a huge system-seller, and Nintendo is going to have to issue the same kind of big temporary BF price cuts that Sony & MS have been issuing this generation. But even if the Switch is up by as much at 50% YoY, it won't be enough to close the YTD gap. It will need to double its Nov. 2017 sales to have a chance of closing the deficit. Personally, I see the YTD sales gap growing to as much as 800k-1M units by the end of the November sales period.

That would leave December. Nintendo systems tend to do well in December, with the Switch selling about 1.5M last December. It is entirely possible that, like last year, Sony may neglect to issue any price cuts ahead of Christmas. If Smash causes significant YoY sales growth (say, +20%) and the PS4 is at most flat YoY, then the gap could potentially narrow by as much as 800k, which could potentially give the Switch a very narrow win.

Ultimately, it's going to come down to what the pricing situation is for Black Friday & Christmas and what effect Pokemon and Smash have on Switch sales. I think it's a long shot for the Switch this year, and I give it maybe a one-in-four chance of becoming the #1 console in the U.S. for 2018.

And I did say it's going to come down to pricing during the holidays and what effect Pokemon and Smash have. But the fact of the matter is that the Switch is almost certainly going to go into this holiday season with a significant YTD deficit against the PS4. It will be hard to overcome that with software alone. If Nintendo has big BF & Christmas price cuts (say, to no more than $250), then the Switch has a very real shot of becoming #1 for the year, especially if Sony neglects to issue any price cut this December. Nintendo will likely need to sell upward of one million more units this holiday than they did last holiday to get even a slim win. It's possible, but not likely. I still think the odds are in the PS4's favor for reaching the #1 spot for total sales in 2018.

But thats expected, and its expected that Switch will have very strong Q4 (definitely stronger than last year), if that will be enough to overcome PS4 difrence, reamin to be seen. I dont think Nintendo will make price cut beacuse they still selling Switch whithout game for $300, they will certanly first start selling Switch with bundled game for that price point.

Hardly anyone expected ps4 to be outselling switch this year, that NPD analyst sure didn't expect it. 

With all the 3rd party big gun games releasing in October this year (Red Dead 2, Battlefield V and Call of Duty) and Sony releasing Spiderman in September, sales can be elevated for those two months and then Sony can address its quieter than normal November (Fallout 76) and December with temp price cuts.

Switch doesn't have much from now until November outside Mario Party.

Outside of RDR2, you think CoD and Battlefield V will do that much in increasing hardware sales after numerous sequels these last several years?

Don't know but since those games normally release in November and that month gets lumped in with Black Friday, it'll be interesting to see for a non black Friday month what those high profile titles do for hardware.  Since the PS4 Xbox One are on their fifth year, games themselves won't do the trick that much but that can change with bundles, etc.