If you poll the casual NBA fan (one that watched some games last season), I am willing to bet they will name kyrie first, more than any one, if asked who plays for the Celtics. The face of the franchise goes to the person who sells the most jerseys and who the fans know most. Until that's Tatum then he isn't the face.
I'm in no way saying he can't be, eventually, but he isnt yet and I don't even think it's even close enough to debate.
Oh, even if the discussion is only based on play then I still don't think it's a debate yet. I don't think it has to be that way until Irving leaves, if Tatum is better, I just don't see how it's really a question now.