Vague error message on config import: Config x depends on x that will not exist after import
Answering my own question, hoping it may help others. The error message above, in my case, indicates a missing configuration file. 

My workflow usually involves switching between branches and re-setting the database to its pristine state. Then I try to import the configuration before finishing a piece of work.    

It turns out I did not commit some field.storage.* configuration files before I switched branches and re-set the database. Then the import failed and complained about missing configuration. Re-reading the error messages more carefully allowed me to understand the underlying issue. 

I used my IDE (phpstorm) local history feature to search for the missing files and restore them. This fixed the issue.