So, Hashino actually told us more stuff in that article. Apparently, P5 isn't going to use the middleware engine Catherine did-- They built their own goddamn engine. This stuff sounds like music to my ears:
They've solidified the themes they'd like to cover in the game. The staff wants to challenge more new things compared to even Persona 3.
Persona 3/4 are awesome, but especially if you consider the remakes, the calendar system has been worn out to hell and back. The fact that they're looking to shake things up is really satisfying to hear.
Hearing this depresses me, though:(
However, he warned that he expects a lengthy wait until release.
Next year, I guess.