2019 is going to be crazy. There are so many good games coming out in 2019 for Switch. Honestly I think 2019 will be Switches best year. I think after that the new consoles will slow Switch sales down, but the Switch will be close to 80m by the time Next gen comes out. Guessing 95-115m sold by the end of its life.
I think Ps4 will have better legs than Switch. 110-130m lifetime sales.
Xbox One 40-60m lifetime sales.
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Want to provide proof? Ive been looking up sales data for all of this. The PS4's best 4th quarter ever was only 3m. That IS insignificant on a 15m needed total. Maybe Nintendo tends to sell better in that quarter than its competition?
Also looking at the data the 4th quarter performs the worst for Sony overall. The 1st and 2nd quarter outperform it.
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Plenty of data here unless you want to claim its false.
https://en.wikipedia.org/wiki/PlayStation_4