"Since I'm sure this is the question you're waiting for, I'll give it to you."

I'm not looking for a question. I'm making the point that there's no buildings out there that won't cost more to rehab or be mothballed than torn down. Using your "DEGC Math", every building is going to be a candidate for demolition because it's always cheaper to destroy than to fix up, if one is intent on looking at nothing beyond those numbers.