Hi Kevin,
Very sound questions. Google's way of dealing with this is the permanently closed label. There are businesses all around me that shuttered years ago and are still searchable, but bear this label. So, at least for the present, this is what they feel is an adequate solution to the fact that businesses close. Google does make some efforts to hide permanently closed listings, but they are still discoverable if a user searches for the name + the old location.
What can be a problem is when businesses don't actually close, but simply move from an old location to a new one. When they do this, there are steps they should take to avoid having their old location labeled as "closed" because some studies have indicated that this can harm their future rankings at the new location if they continue to use the same phone number as was used at the old location, as well as signalling to customers that the company may have gone out of business.
If you own retail properties with tenants who move rather than closing, a nice thing to do for them would be to teach them how handle GMB so that they don't end up with that "permanently closed" listing. I outline how to do this in the "permanently closed" section of this blog post: https://moz.com/blog/delete-gmb-listing
Might be something to bookmark for future reference!