Yes, strictly speaking, an archive or a research library is more likely to be long-term storage than a public library (of course, the division is not clear-cut-

Yes, strictly speaking, an archive or a research library is more likely to be long-term storage than a public library (of course, the division is not clear-cut--and some public libraries have substantial archival research holdings). It's pretty routine for libraries to get rid of materials that aren't being used by anybody anymore. But it does take control over the process, the choice of what to keep and what to give up, away from the libraries to some extent.