From the Touhou Wiki's transcript of his AWA 2013 panel:
Q: Are the PC-98 games considered canon compared to the Windows series?
ZUN: There are a few contradictions in the story when putting the PC-98 and Windows games side by side, but I would take reference from the latest games to consider what is canon.
Q: Will you consider bringing back very old characters from the series?
From the Touhou Wiki's transcript of his AWA 2013 panel:
Q: Are the PC-98 games considered canon compared to the Windows series?
ZUN: There are a few contradictions in the story when putting the PC-98 and Windows games side by side, but I would take reference from the latest games to consider what is canon.
Q: Will you consider bringing back very old characters from the series?
ZUN: I won’t say no. There’s your answer.
Does that mean... we're to expect them coming back in the near future?