I mean its not on the PS2 but they've already got their engine up and running on the PS3 with Catherine by the same development team.
They have the same problem all these other developers from Japan have. It shouldn't take well over a half decade to develop one game. Persona 5 isn't gonna be released until 7 years after Persona 4.
meanwhile in that same time span we've gotten:
Tales of Vesperia
Tales of Graces
Tales of Xillia
These two will both be out this year
Tales of Hearts
Tales of Xillia 2
This one was announced for a world wide release likely to be out closer to when Persona 5 releases.
Tales of Zestiria
The Tales series is the only one putting work in the JRPG space.

are you talking about??
Persona 5 is not running on the catherine engine.
Team Persona’s first high-definition game
Catherine outsourced a third-party engine. With
Persona 5, Atlus is making use of a new internal engine. Hashino said this engine will allow them to smoothly convert their ideas to reality.
Read more at
http://gematsu.com/2011/08/persona-5-uses-new-internal-engine#cHz3QA3GFIRazdFP.99
http://gematsu.com/2011/08/persona-5-uses-new-internal-engine
Persona 5 comes out THIS YEAR in Japan and next year in the USA.
Persona 5 was confirmed to be in development since 2011.
http://www.ign.com/articles/2011/08/31/persona-5-is-in-development
if it releases next year in the US, that will make it 4 years of dev time which isn't too bad for a game of it's scope coming out on a new system with a new internal engine. It isn't like Persona 5 was being worked on since 2008 if we were to speculate.
As for the tales games, I don't really pay attention to them anymore. they're not as big as a final fantasy release and they just seem to be B-tier RPG games. Last one I played was Tales of Vesperia and it was alright at best, nothing really to get hyped over imo.

I didn't even play any of the PS3 iterations as I just simply didn't have time.
Since 2007, atlus released Persona 3, Persona 3FES, Persona 3 Portable, Persona 4, Persona 4 Golden, Persona 4 Arena and coming this year are Persona Q, Persona 4 Arena Ultimax and next year Persona 5. The releases in between each mainline persona game are usually chock full of content. I bought Persona 4 golden 40 hours after playing the PS2 version via emulator and it felt like a fresh game. It was more than just a simple prettier port that was portable.
I lost interest in JRPGs for a while after being jaded with FFXIII. Persona 4 rekindled my interest and now I can't get enough. I still have FFX HD sitting in it's case.