Yeah, at this point it seems only NIS and Compile Heart believe so much in PS4 to have exclusive titles for it. Eh.
It's practically no different with the western developers... 90% of all games released to-date are all cross-gen, and will remain so well into the year's end, and maybe even first-half of next year.
The important thing is that the first wave of support needs to be strong. As far as year 'one' (sarcasm) Japan support is concerned, I'd say the line-up for 2015 is pretty solid, cross-gen or not.
There's cross-gen spin-off releases from practically every major third-party Japanese franchises (DQ, FF, WE, BIO, etc ), potentially 2 flagship titles ( MGS, Persona ), and a good mix of titles of various other niches, both big/small (Gundam, Disgaea, EDF, potentially IM@S, etc ) that all a dedicated fanbase that will buy hardware for said games, however small the base is.
The big question now is Sony. Sony's big problem is that they have no 'system seller IPs' in Japan that's coming out anytime soon. Bloodborne could potentially be big, but that's only one game. Will GT7 and Minna Golf be released next year? Honestly, Sony needs to effing get both those games out ASAP.
However, their own output aside, I say that Sony has done a decent job of positioning the PS4 as the 'hardware' to get if you want the best of everything.
Sure, many games are cross-gen, but there's enough of 'cross-gen without Vita' + 'cross-gen without PS3' + 'PS4 exclusive' in-between that could potentially sway the audience into thinking "eh, I might as well get a PS4 since then I'll get to play everything."
It's not all that great, but I'm a lot more optimistic for Sony's 2015 now than I was a week ago. Even as a cross-gen game, I never imagined DQ coming to PS4, and Persona 5... I was assuming they'll go the cross-gen late port route, but damn, simultaneous release!