Eh, I really think that if they had a "Director's Cut" style PS4 port in mind for Japan they would have announced it this weekend. Ports usually come 12-13 months after the original release. But console Tales games they intend to announce and release between October-January that same year are usually announced around this time. Factoring in this, plus the way that all evidence of a PS4/PC version is coming from the West aside from a PS4 ad in Japan (which doesn't really seem like strong evidence). and it could just be a similar situation to Godzilla and J Stars.
That they set up Berseria as their next upcoming console release in Japan, even when it seems like it's over a year away, makes me think they've decided to move on and not to put as much into Zestiria's post-release games/material as they probably would have had it been received better.