It is definitely second person plural. I have heard my daughter use it (deliberately ironically) many times not in the form of questions, like "Chat, today we'r

It is definitely second person plural. I have heard my daughter use it (deliberately ironically) many times not in the form of questions, like "Chat, today we're going to be making toast." I admit that I have never heard it used in anyway except as a noun of direct address, so it may not be a full-featured second person plural pronoun.