So we know something will be revealed on the 24th of November. If you're optimistic and think it's an unveiling of Persona 5, then we can make an "educated" guess as to what the Japanese release date will be. Persona 3 was unveiled in March 2006 in the Famitsu Magizine. Persona 4 was unveiled in March 2008 in the Famitsu Magazine. Persona 3 released July of that year and Persona 4 released December of that year.
*conspiracy hat on*
March to July = 5 months
March to December = 10 months
November 2013 + 5 months = April 2014
November 2013 + 10 months = September 2014
Following the pattern...
November 2013 + 15 months = February 2015
THERE YOU HAVE IT FOLKS,
Expect Persona 5 to be released anywhere between Apr 2014 - Feb 2015
Feel free to make crazy guesses of your own.