noticeably last-gen console, it looks like developer Atlus doesn't see any reason to jump ship for the sequel. An article at Bloomberg Japan (via Siliconera) listing upcoming Atlus titles has Persona 4 coming next fiscal year for the PlayStation 2. (Note: image above from Persona 3.)
The word doesn't come directly from Atlus, so there could be a typo or miscommunication (major news outlets are prone to mistakes every now and then). The platform, however, would not be surprising given the company's comfort with developing for the PS2 and Sony's continued success with the now value-priced system. As Siliconera notes, the timing of Persona 4's release could make it a tie-in with Persona -trinity soul-, an anime series due out next year.