such as being here on a student visa so they don't actually need an SSN.

 
Certainly those that have figured out how to stay here legally (visas, green card, whatever) don't have a problem, they should have the federally acceptable documents to get a Real ID issues. Those that don't, well, clock is ticking there. They can probably get by on their Korean passport but that has an expiration date.

 
I think you're right that those without good docs will not be traveling -- which probably means those heading to K-town might be able to find bargains but probably also would need to be connected to the K-community there. Kind of sad. But many might choose to return home. Both argue for fewer touring girls, but not sure if that means smaller markets don't see the girls or not.

 
Alternatively, as has been mentioned before here, some seem to be traveling by other means, and with concerns about ICE might actually suggest mid-market preferences.

 
Perhaps just more 90 day wonders showing up.

I wonder if you present an overstayed foreign passport, can you still fly domestically(within the US)?  Because without a real id or your foreign passport, you have no real options to airplane.