Marshall Breeding has published "Library Systems Report 2018" in American Libraries.
Here's an excerpt:
LSPs [Library Services Platform] are now the mainstream approach for supporting resource management and daily operations of academic libraries. These products have not yet become ubiquitous, though they continue to dominate in new procurement scenarios. A significant proportion of academic libraries rely on longstanding ILS implementations. A large portion of these libraries are engaged in selection processes that will culminate in the continuing decline of the ILS in this sector.