Before 2020.

Hahahaha Hahahaha 

It isn't. 

http://www.vgchartz.com/analysis/platform_totals/

6 PlayStation 3 (PS3)   86.86

7 Xbox 360 (X360)    85.78

Wow people are saying "never" still??? Though it's not that embarrassing as it's due to bias and not idiocy.

Their judgement is simply clouded by a Mario and Zelda haze.

78m shipped by March 2018
93m shipped by March 2019
103m shipped by March 2020 (at least)

Bwahaha! That's a joke right?  The PS4 is still outpacing the PS2.  Sure, I don't think it will last forever, but 100M is a given.  Sony actually lowballed their shipments for this fiscal year, so it'll probably be at 80M by March of next year.  Before 2018 is up they'll be past the PS3's ~87M.  Sorry, but it is going to pass the Wii.

PS4 won't reach 100 million, so never.

After your horizon prediction I'd hope you'd have learned your tendency to think negatively about PlayStations prospects.

100m+ is a certainty, only launching ps5 in 2018 could stop it.

Well its definitely going to happen that's for sure, but when? Who knows, too many big titles still to come that will push it, Red Dead 2, most like Grand Theft auto 6, last of us 2, God of War, Death Stranding, Gran Turismo, Days Gone, Detroit etc etc. I think the PS4 will sell over 110 million before its discontinued.

If watching "The Price Is Right" with Bob Barker has taught me anything.

I would say,... 2021 Bob!