We've reached the end of the traditional library.The network
and digital items (that contain information) are easier and more
valued that traditional items (books,print journals, dvd, etc.)
see (Buckland's automated library) and therefore the traditional
jobs of reference, selection, access services, and
cataloging.
The modern library (maybe the digital library) is where the
contents are digital as well as the tools
All roles can bleed into each other and the top three are much harder to do than the last so there will be fewer of those positions