IFC4 introduces a new model view definition, Design Transfer View
http://www.buildingsmart-tech.org/specifications/ifc-view-definition/ifc4-design-transfer-view
The existing implementation for IFC to Revit is Opening/Linking, not importing and updating. This means that IFC in Revit will never be more then an underlay for native Revit modelling.
Implementation for Design Transfer View will require importing/updating. This will include contexts such as IfcProjectLibrary to facilitate Product/Object Library exchanges. And also to enable partial model update/manipulation. This will also help permit placement of model relative to nominated shared coordinates.
The implementation for design transfer would also require further improvements in converting IFC concepts into native Revit elements from the existing implementation. It would mean Revit becomes capable of using IFC in a design process instead of just a means of creating a deliverable.