I mean it's down from last year pretty heavily in the past few weeks.Well last year they had FFXV and Yakuza 6 in December. I honestly wouldn't worry about the PS4 in Japan, it's doing well enough for publishers to support it and even when the Switch takes over publishers will still have little to no reason, to abandon the PS4, since contrary to what Resetera's Media Create community would like you to believe the system still has very healthy software sales for japanese games, both in Japan and outside. In fact, due to devs not being able to rely on the low dev costs of 3DS games, I actually foresee more and more projects, that used to be 3DS only to make their way over to PS4 next to the Switch.
Inazuma Eleven is a first example of that, I doubt Dragon Quest will go back to exclusivity either and I wouldn't be surprised if the next Yokai Watch goes PS4/Switch too for instance.