Doesn't really matter since they will essentially be a "paper" loss since WT bought many of those properties either dirt cheap in the 70's and 80's or back on the early 1900's. Note excerpt from NYPost Article:
"That year, they sold their former book plant at 360 Furman St. for $205 million - more than 50 times the $3.9 million they paid for the 14-story building in 1983, according to records"
So even the Real Estate market is going down it will never dip below what they unitially paid for the prime real estate. Besides Brooklyn Hts is a VERY desireable area to live in so I doubt it would drop that low.