Wasn't it also it would kill Mario Kart Wii? 

Possible, I tried to find it but couldn't. Maybe it wasn't Leo-J but someone else but yeah Mario Kart Wii was in there too since the game release very close to one another.

It was Leo, just might have been its own thread. 

I haven't participated in this thread since March, but here's my updated analysis.

First some relevant charts:

The Switch's 2018 is trailing the PS4's 2015, but only by a narrow 3.9% margin, or about 87k units. Close enough to where the Switch could easily pull ahead by year's end. However, that's a tall task. Q4 2015 was the PS4's best holiday quarter to date. In order to surpass that and make up for its slim deficit as of end-Q3, the Switch will need to have 37% YoY growth in Q4. Various bundles, Pokemon Let's Go, potential Black Friday price cuts, and especially Smash ought to drive significant YoY sales growth, but will it be enough to put the Switch ahead of what the PS4 sold in 2015? I'm not certain. So, I will have to stand by my initial odds of 70-30 in favor of the PS4. The Switch has a shot at taking the lead, but it's a bit of a long shot.

It depends on the kind of deals, and if they have them for both BF and in December. The PS4 did have its best overall Q1-Q3 period to date this year. However, that is entirely due to God of War and Spider-Man. Outside of April and September, the PS4 is down slightly from last year. But it is also slightly ahead of 2015 even ignoring April and September. Nevertheless, the PS4 is so far 370k ahead of what it sold in the first three quarters of 2015, which gives this year an edge going into the holidays. Last year, the PS4 got cuts for BF, but not in December, and as a result December was way down YoY despite November 2017 being the PS4's best month to date. In fact, despite beating the XBO by over 200k in November, it was in turn beaten by the XBO by nearly 300k units, and as a result it actually just about tied the XBO in Q4 last year. To beat 2015, the PS4 will need to sell at least 3030k in Q4. If Sony does a repeat of last year and only issues cuts for Black Friday, then it likely won't get to that number. However, if they also issue cuts in December, Q4 could potentially surpass the 3M mark, putting 2018 on par or ahead of 2015.

It depends on the kind of deals, and if they have them for both BF and in December. The PS4 did have its best overall Q1-Q3 period to date this year. However, that is entirely due to God of War and Spider-Man. Outside of April and September, the PS4 is down slightly from last year. But it is also slightly ahead of 2015 even ignoring April and September. Nevertheless, the PS4 is so far 370k ahead of what it sold in the first three quarters of 2015, which gives this year an edge going into the holidays. Last year, the PS4 got cuts for BF, but not in December, and as a result December was way down YoY despite November 2017 being the PS4's best month to date. In fact, despite beating the XBO by over 200k in November, it was in turn beaten by the XBO by nearly 300k units, and as a result it actually just about tied the XBO in Q4 last year. To beat 2015, the PS4 will need to sell at least 3030k in Q4. If Sony does a repeat of last year and only issues cuts for Black Friday, then it likely won't get to that number. However, if they also issue cuts in December, Q4 could potentially surpass the 3M mark, putting 2018 on par or ahead of 2015.

Well, it did absolutely squat to help sales, then. I guess $199 is the way to go for the Slim. Maybe $299 for the Pro to boot.

problem was xbox was like 159-200$ with like 3 games the whole month of December which really hurt ps4 sales .

Show me these $159 deals, the lowest I can find is $199 in December.

i cant  show them but it was as low as 159$ or around there iirc.