The one thing I would make sure to be aware of next time is the decreased amount of time you have to find a new tenant. 

If you could decrease the gap between your holding cost and your rent, I think that would be preferable to walking away or eating a significant loss.  

This vastly increases the pool of available buyers and should increase price and decrease hold time.

@Brianna Schmidt Great point, I never thought about the decreased payment with a 30 year mortgage being important to DTI.

Some more winners12) Insurers-decreased chance of an empty house being broken into by copper thieves or other vacancy issues.13) Building supply stores- Will sell additional materials to the end buyers who are improving their home.14) Private mortgage insurers (if there was one involved) will not have to pay off on a foreclosed property.

As you take deprecation (or are allowed to even if you don't) that decreases your basis.

a strategy @Manny Cirino that has been around a long time is master leasing distressed properties for JV cash flows, as the foreclosure auction approaches the rent decreases, it's not unusual to charge 80 per cent of market rent, and 70 percent of market rent last 90 days of foreclosure.Jv s can be anything, 50 50 etc.

However, that will decrease cash flow due to higher payments ($882 vs $613).

Sell potato chips and other grocery items that are slowly decreasing in quantity, but rising in price.

In a disaster scenario like that of 90% depreciation in price I would probably be more worried about guns, ammo, food, water, etc not my real estate portfolio =D.I use income decrease of 10, 20, 30 % based on how solid I believe the market is but I would say that if you have to use 40% or more then your market would be highly volatile and you may have to reconsider your stability of your income if we're talking about rentals.