I'd like to see it, and all the elements for making it work are already in-game too:
The Priority Pass Exit already makes the queue pause even when there's space ahead that guests can move into. Why not add something similar that can be triggered by Display Squencers?
Add in a property for it that makes guests that have passed a "Pre-Show Gate" look at specified scenery objects (the way Vista Points already can), maybe make that property triggerable too if you want them to look around, and you've got a full-pre-show setup.
EDIT: In fact, you already have the ride Ticket Booths that you use to connect queues to paths, and those can be placed from the Shops and Facilities window. Why not have "Pre-Show Gates" work like that? Then you just route your queue through them!