I don't how many of you actually care if it is or not, but as of 3 days ago a representative of ATLUS USA stated that PQ is canon. He doesn't say how, because it would spoil the story of Persona Q. Here is a link to the interview from siliconera.http://www.siliconera.com/2014/06/20/per...

The part where it's actually said is in the last paragraph. Everything else is talking about the game mechanics.