…is what I would like to say, but it looks like it has been more or less revealed as an anime project for the series.
Altus was teasing the teaser about a day back with a live-action trailer, featuring people talking about a certain mayonaka-tv (translated as midnight tv, fans of P4 will know what it is) with the trailer ending off with a link to the teaser site.
The teaser site, on the other hand, shows a TV with a countdown timer which will end exactly on 12 midnight on the 11st of April, which is today. That is also the day where the protagonist of the game starts his journey in Inaba in Persona 4.
Although there were speculations about the announcement being Persona 4 Portable (which i really had hoped for), it looks like the teaser was about the anime project of Persona 4 after all. Viewing the teaser website through their mobile platform reveals a particular “Persona 4 アニメ”, more or less sealing the deal as an anime project. The project will be produced by Aniplex.