There's also a pretty cool concept art image of what the stage will look like in the theatre it'll be showing in:
They already cast someone for Tigress: Wushu athlete and model Janice Hung. Source: https://news.abs-cbn.com/life/04/15/19/wushu-athlete-janice-hung-to-play-tigress-in-kung-fu-panda-live
I'm surprised they got someone so relatively quick for Tigress, especially when there's no word yet on who will be Po. Looking forward to a full cast list sometime soon.