I like the idea of single-units but the setting has to make sense, and the economics virtually never make sense.

Typically, the economic demand drivers are the same across all successful markets. 

I've heard a lot of banks are not offering HELOCs to customers at the moment given the economic turmoil caused by Covid.

We didn't know what was about to hit us and a year later the house was extremely underwater due to the subprime mortgage crisis.

Current and past population trends and economic data is helpful, but in deciding where to buy real estate, I would really love to glimpse the future. 

Life happens and people will move and you will not have 100% economic vacancy even though you may have 100% physical vacancy.

As long as the demand is high and the supply is low there will be growth in home pricing as well as an increase in new builds to accommodate.In areas where appreciation has been more speculative and the market doesn't have the economic drivers to keep going, I believe there will be major corrections.

Still goes back to supply and demand economics.

Economic conditions contribute - if the wage base of the population is under what homes are selling for, it also pushes more people into rentals. 

If it is feasible and economical, the sister refinery in my town will do the same conversion.