I've already archived our email programs from 2017, but I would like to also start archiving our assets that we have not used. If I archive assets (images/docs), but don't realize they are being used by a template or older email, will that break the links?
Have you been able to test this. If not, it should not cause anything to break as assets that are in use will work even after they're archived (even things like smart campaigns will if they aren't deactivated). Archiving really has more to do with eliminating auto-suggest/search and reporting.