While there certainly have been rumours about the launch of Persona 5, the final release window has been revealed via the earnings release of Atlus parent company SegaSammy.
According to the report, Persona 5 will release between October and December 2015, and thats both in Japan and North America.
Many believed that while Persona 5 could certainly release in Japan within that timeframe, a North American release would be pushed into 2016. Now we hope that the European release will be set within that window as well.