I think it'll be less than PS3.

It all depends on where japanese 3rd parties focus their efforts going forward. To me it seems they're allocating fewer resources than ever towards home consoles, and more towards smartphones/tablets and dedicated handhelds. So my guess is less. 8.5 mill seems realistic. But if jpn 3rd parties redirect resources anything can happen.

Around 8 million is my guess, Japanese games more and more are moving away from home consoles to portables. I say the Vita has a better chance than the PS4 in Japan. But anything could happen.

More than Ps3 and 360 combined easily. The Wii U will probably sell as much as the Ps3 and X1 will have the same as 360. So 23mil for all 3. People saying it will be less are really underestimating FF15, KH3, GT7 and MGS5. I mean this gen we got the worst FF ever and no KH.

More

Japan is looking good so far. We got Final Fantasy 15 and Kingdom Hearts already coming. We really need another Level 5 developed Dragon Quest on PS4

Do people here honestly think it will do less ? This generation altogether, consoles have being able to pull off 20 million in japan. So why expect less for a platform that has no competitors in japan ?

10-15Million

While it might sell a bit less than the PS3 (I think it will be roughly the same), I don't really understand this idea that Japan has abandoned home consoles. Yes, they've tailed off this generation but that's true in the west, as well. It's not like portables just now got big in Japan, either.

As far as developers abandoning home consoles, I don't see that at all. Anyone who watches the COMG! lists will see a sea of red (PS3) more often than not. The 3DS has had some recent smash hits but the sheer volume of smaller, Japan-centric games being released on the PS3 is staggering.

The PS4 will still get those games and they will still be popular. Games like Yakuza, the Warrior series, and the different fighting series aren't suddenly going to die out.

more 1.5-2.5 times more than what ps3s will end up

low competition console wise

starting at a lower price

if what were hearing about its ease to develop and triangle time turn out to be true than that should also help

100 million on japan,
300 million on us
500 million europe
187 million on Brazil