IF he is still alive he would only have disappeared for a very very serious reason (possibly danger), so serious that his family had to declare him dead. The best way to achieve such a thing legally is for instance through a Witness Protection Program. Things like that are not a game. Therefore it would not make sense for him to leave all sorts of clues that could blow his cover.
So no, I find it unlikely that IF he is alive and IF he would return to his old identity, that he would do it at some sort of magical date, play a bit with numbers etc. You don't toy with things like that, it would be a random date and probably with some previous announcement.
As far as a WPP, such a program does strongly discourage any contact of the person in the program with their loved ones in order to not endanger the program. Often the people in a WPP need to testify as a (crown)witness at the trial. A WPP usually lasts untill the trial or if the threat persists, even after the trial.
Remember the files the FBI released recently on MJJ. A man had threatened to kill MJ or fans at his concerts. That's a mass murder threat. Suppose such a threat happened again around 25th June, security would be highly increased and the concerts few weeks ahead would be cancelled. MJJ would have to serve as a witness, especially if it appeared that someone indeed tried to kill him (attempted murder, propofol) despite increased security. They could have saved him in hospital. Blood and tissue tamples would be send to pathology lab and examined for possible toxification, he would have had a throrough medical and a report would have been drafted to serve in the investigation.