It's fascinating to look back and see the lifetime sales of every console. I totally forgot that the PS2 is still ahead of everything -- it's not even close -- as it towers over the number two spot, the PS1, by over 50 million (PS2 is at 155m versus the PS1's 102m). Then comes the Wii at 101m, the Xbox 360 (remember how powerful Microsoft was last generation?), and the PS3.
The PS4 is steadily climbing on that chart, as Sony has announced that the PS4 has shipped 60 million as of the end of March 2017. From April 1 through that same time in 2018 (its fiscal year) Sony is aiming to ship 18 million more, which would skyrocket it above the NES, currently sitting just above it at around 62m in sales, and the 3DS, which is at roughly 66 million. If Sony hits their 2018 target the PS4 will already be the 10th best selling gaming device of all time, with more room to grow.
With this curve it's possible that we'll see a longer console lifecycle with the PS4. Especially so, if they're sticking to the "Pro" style of delivering iterative devices rather than a full blown PS5. I guess we'll have to see how much the Scorpio changes the landscape, if at all.