Remember in the episode the newspaper says "Stan Pines Dead"? Well what I was thinking is that since we now know Stanley is real, that the Stan Pines they are talking about is Stanley. I know what you are thinking "Then Why Is Stanley Alive?" Well, that is stanley from another dimension where he didn't die and Stanford died. This is possibly why we don't see Stanley in this universe/dimension. Or, the theory could be the other way around and Grunkle Stan could be Stanley and Stanford is the one dead.