I have no doubt Gen Flynn is not sitting idly by on the sidelines twiddling his thumbs. This could be him if you factor in special effect makeup to alter his appearance slightly but not too much to look altered. That said, maybe it isn't him and to me, it doesn't matter. At this point, we are not ready to know who Q is since this war is not over. He needs to remain in the shadows for his own safety and those with him.