Well PS4 won't stop selling after PS5 releases, but yes, by current situation I expect PS4 to reach 120Mm at most 130M. PS3 died quicker after PS4 released because its gen was very long and it never got to the 100-150 pricepoint really. PS4 may achieve that. PS1 and PS2 both sold very large amounts after successor release.
But I agree with you that Sony launching on others territories later in the lifetime than they do now will probably make the tail smaller as well.
PS1 and Ps2 both sold high numbers (around 20-25m) in Japan though something I don't think PS4 will achieve and will impact that, both those prior systems had very different situations in the industry to what PS4 has today as well.
Sure PS4 won't reach similar numbers to those in Japan, perhaps half. But at the same time, Europe and RotW growth a lot and will offset the Japan loses. But on this gen PS4 have faced strong competition from X1 on USA and that with Japan will make a great diffence.
X360, Wii also were, so?
And considering PS2 sold over 1.5B SW the notion of CD/DVD and pirating making PS1/2 succeed is false. It's attach ratio was just as good as the best consoles, even more considering the late adopters would have lower attach ratio and drive it down.
Yes they are, and Wii also was quite popular on weaker markets also, cheap and pirated console is great recipe for selling good even on weak markets.
One of reasons why PS2 was so popular even in weaker markets is definitely fact that is completely pirated for very long time and very cheap in same time. I talking about weak markets, offocurse that on West and stronger markets people usually don't pirate in any case, I live in Balkan in Europe and plenty of people had PS2 here but almost nobody both even one original game, I personally didn't both one single original PS1 or PS2 game. :)
Brazil was similar up to X360 (that also sold great because of pirating, but with XBL there were a lot that forfeit pirating to play online). Sony didn't even officially launch PS1 and 2 here due to pirating.
But all summed, those sales were the smaller part of the pie, and in Brazil and probably a lot of other countries gone by grey market on USA imports.