With PSYCHO-PASS: Sentaku Naki Koufuku releasing this month, Dengeki Online did an interview with Mages. producer Asada Makoto and PSYCHO-PASS anime producer Mori Akira.
Q: Is there a season 3 for the PSYCHO-PASS anime?
Mori: We are considering of developing it.
The story has expanded this far, so its really hard to imagine what else they can do for the series. Maybe a prequel series about Kogami before he became a enforcer.
Source: Dengeki Online