The value of luxury condo The One is now about half its asking price. What happens if no one wants to buy it?

"PS- How do you deal with any asset that has lost half its market value? Some combination of debt written-off and restructuring/ financing?"

depends...were you the 45th president of the united states of america?

You finish the project and maximize your revenue. All secured lenders then get paid in priority sequence. Your senior secured lenders get paid first, then funds go to those in 2nd position, etc until there is nothing left. Typically equity investors (ie Mizrahi) get nothing unless there are funds left over.