If i want be honest, i never predict PS4 above PS2 this gen, i have always said that more than a prediction was a hope.
http://gamrconnect.vgchartz.com/thread.php?id=184590&page=1
In any case, when i make this thread, i didn't was so sure (some like 20% of probabily in my heart)...But...
By August Sony have annunced 10,000,000 sold, and VGChartz was 1,000,000 undertracked!
After this, my hope is rise... and is rise again after the 538K in September NPD! (My prediction was 475K)
At this point, i was 50% sure of my prediction... but by end of November/Starting December... i have starting to really believe in my prediction. :O
PS4 was almost for sure confirmed to sell 20,000,000 by end of year, maybe even 21-22M, as much people have predict, so, i was almost sure that my prediction!
And now is Jenuary... Sony have annunced 18,500,000, and it have leterally crushed all my hope.
So ok, PS4 don't will break 170,000,000 as i have hope...
But yeah, now my PS4 prediction is how much have predict by end of 2013/startiing 2014: it will be 120,000,000 to 140,000,000, 130,000,000 seem ok.
(And please, don't comment my englesh! è-é )