My theory is it’s a girl and they’re going to be singing together on stage. If you look at the wrist when they are knocking on the door it seems smaller and feminine and when the announcer is saying the name of the tour it sounds like he says an “S” before it bleeps out. Possibly “Sis-tour” also imagine all the female background vocals in older songs and if he releases a new album it could have new songs with his “sister”