we expect 0 nurses if 19,000 leave. we have 0. keeping 19,000 nurses is more than we expected, we expected 0.
We only expect 0 nurses if 19,000 leave and we have no intention of replacing them
The need to replace them means we expect 19,000 will leave and will be replaced with 19,000 meaning we expect to have 19,000 nurses
Look, it's clear we're not going to agree, most of the population will agree that keeping/replacing does not mean you end up having more of something