DispatchingEntityPrefetcher should be moved to DataModel Services, where the interface is defined.
There are no dependencies on Wikibase itself in the implementation that would prevent from moving it.
Similar should happen to DispatchingTermBuffer. In this case the PrefetchingTermLookup the dispatching service implements should be also moved to DataModel Services. It combines TermLookup and TermBuffer interfaces that are both defined in the DataModel Services.
The move of above mentioned classes and interface should be part of a single release of the Services component.
Other Dispatching services defined in Wikibase at this point (DispatchingEntityRevisionLookup and DispatchingPropertyInfoLookup) should not be moved as their related interfaces are also defined in Wikibase repo.