An update to the official Square Enix website suggests that the developers could be considering a Summer 2016 release for Final Fantasy XV. The suggestion is founded in a roughly 50 question survey aimed at people who are considering buying either Final Fantasy XV and Persona 5 when the games are available.
The questionnaire (via Gematsu) asks users ‘if Persona 5 and Final Fantasy XV came out at the same time, which would you prefer?’
From what we know, Persona 5 is set to release in Japan this Summer, with a vague Western release date. With the questionnaire looking to gauge which game fans would be more interested in purchasing if Final Fantasy XV and Persona 5 released at the same time, it's not crazy to assume that Square Enix is considering a Summer release for the highly anticipated addition to the game series.
On top of that, the Final Fantasy XV started out as Final Fantasy Versus XIII which was revealed in 2006 before ultimately changing to Final Fantasy XV… So, Final Fantasy XV has been in development for quite a while.
Square Enix is planning to announce the game's release date during a presentation in March, so we will find out a solid release date then – but here's to hoping for a Summer 2016 release date.