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.
