Don't be surprised if that parade does not get massively rethought and redesigned after Tianjin. If its not led by a column of firefighters, I will be amazed. A purely military parade will not go over well right now.
The Tianjin industrial explosion, mostly likely an accident, has absolutely nothing to do with WW2. It makes zero sense to adjust anything at all in the WW2 victory parade due to an unrelated industrial incident/accident.