If his retaining wall is being affected it is not clear who has responsibility.How do you know that the contractor he hired won't worsen the problem?

I fully own my first rental, so the only option I see beyond waiting and saving for a down payment is to take another loan against the first rental... which in your doomsday examples doesn't increase my likelihood of success by any measure, in fact since it will end up costing me more money it only seems to worsen my situation. 

Getting legal guidance would be my first course of action to avoid anything that could in any way worsen the situation for you or your tenants.Here's a document with some HIPAA guidelines, including additional links, that may provide helpful information: https://www.hhs.gov/sites/default/files/february-2020-hipaa-and-novel-coronavirus.pdf

What if they worsen and it's uninhabitable?!?!

Two big reasons we're seeing here- their owners are likely the type to have poorly managed personal finances as well, or their properties performance has worsened in the light of eviction moratoriums/job loss/ethical ambiguity of poorly selected tenants. 

Dealing with a buyer with all the cash necessary to purchase means they won't be calling you two days before the closing to say their financing fell through and they can no longer buy.Just in the last 30 days, I've spoken with three different investors who were informed within days of closing that their lender was either withdrawing their financing commitment or radically worsening the terms (unless a sizable fee was paid to them).Not the buyers fault, perhaps, but that fact doesn't help our seller, who still doesn't get their sale.

Particularly if the economy worsens and lower income demographics are hit particularly hard.

The home inspector did not raise it as something that must be fixed, and it seems to have worsened since that time.

Terms have significantly worsened since Covid 19 struck, but there are some that are still lending.  

I would be particularly interested in people who are house hacking a SFH during this pandemic.It is one thing to get a family into a unit in a duplex, but I can see more challenges with getting multiple separate individuals to be your tenants/roomates during a pandemic.Also, its usually recommended to do month-to-month leases for SFH house hack so you can feel your tenants out.But given financial risk, that is a harder decision to make.Thoughts related to this:(As the economy continues to worsen...