Eminent domain means a government taking for fair market value.
So in this scenario, a city takes a mortgage note for FMV. Let's assume a $100,000 house with $120,000 owed on the note, and that the city pays the mortgage holder full value for what's left on the note. The city now has a note and a lien on a $100,000 house for which it paid $120,000. What are they going to do at this point?
Forgive the homeowner's $120,000 debt in exchange for a $100,000 note from the homeowner, issue the homeowner a 1099 for $20,000, and sell the note for $90,000. City loses $30,000 grand on the deal less city income tax paid on the 1099. So basically, it's a miniature, tax funded, bailout for homeowners.
What purpose does that serve? What happens when property values drop again? Is this program going to available to everyone in the city, or just people of a certain income level? How about owners of rental properties?