Rising economic vacancy will impact your income and your cash flow. 

As has been mentioned, time on the market can have an impact on a sellers motivation, but I might add also be a telling take as to how unmotivated a seller is to sell their property.I would agree that SFR owner occupied sellers have many more reasons, including emotions, that guide their motivation.When it comes to short sales and foreclosure it really all depends on the bank.

However, I fail to see how/why it would have much (if any) impact on individual landlords. 

I would do a cost analysis and determine if any of those factors would impact your cash flow compared to trading up. 

An influx of supply, in a vacuum, will drive prices down.The flip side, however, is the impact on demand, which is always hard to peg.

It's not uncommon to bring in structural engineers when you're doing work that will impact the structural integrity of the house. 

Keep in mind that real estate investing is all about making sure you will do things that are of benefit and not detrimental to you. 

It will not impact things.  

Of course, property values can also go down, but both rents and interest on a note should not be impacted unless something crazy happens.One challenge with notes is keeping your capital deployed.  

If the crash affects the tech sector, this will have the greatest impact on the Seattle market just like 2000.