I ended up servicing the loan out of my own pocket for a couple of years--another $400K down the drain but ultimately the rebounding prices will allow me to recover that when I sell someday.Moving on to your questions, which are two distinct questions with different answers. 

This was during the downswing of the market and many people felt that these condos would be worth a lot more when the market rebounded.

.* Houses prices: I agree, prices have rebound, even surpassed 2007 in Seattle directly.

Prices started rebounding in 2010, though they haven't reached the 2007 levels yet. 

How do I quantify the impact the slowdown in the oil economy has on the value of the cash flow (other than increasing my calculation for vacancies which I am sure will increase if oil does not rebound soon)?

I also knew that the real estate situation there had bottomed out, and that it would rebound in a few years.

“The public’s increasing willingness to rent – due to the difficulties many people are encountering getting into the region’s expensive real estate market – and forego property ownership is pushing many would-be home owners who are able to afford higher rental rates into the market.”According to the report, multi-family investment activity rebounded in the first half of 2015 with 26 deals (more than $5 million) valued at $370 million compared with 20 transactions totalling $186 million in the back half of 2014.

With the tax code capping deductions of state and local taxes at $10,000 and instating a $750,000 limit on deductible mortgage debt, homebuyers and potential homebuyers are fleeing high tax areas, such as New York, Chicago, Denver and Washington, in favor of places like Florida where there is no state income tax.Recent data shows that the home market could be on the rebound.

If you are investing for appreciation, what if market turns then you have to wait for the rebound to make anything?

In most areas things are on the upswing, possibly even nearing the top of the cycle - prices have increased, activity is up, demand is up and things have rebounded from the great recession however that's not always true everywhere.