If someone uses BIM in their projects, they put different levels of efforts in the BIM model. Therefor there are several BIM levels to determine BIM integration and its usage in the projects. As we can see from above there are 5 levels from 3D to 7D. I will briefly describe them to have an understanding of BIM potential.

It is the first stage for BIM, which includes 3D model of the building. This model is geometry with collection of objects such as walls, columns, windows, doors and etc. It is a perfect way to visualize what the future building will look like. Also it can be used for rendering to the client, clash detection and quantity lists.

The construction of the 4D models enables the various participants (from architects, designers, contractors to owners) of a construction project, to visualize the entire duration of a series of events and display the progress of construction activities through the lifetime of the project.(taken from http://web.stanford.edu/group/4D/)

If 4D BIM is time then 5D BIM involve cost. As I said before that 3D BIM includes quantity of the objects inside of building geometry so there is a possibility to use the quantity for establishing the price of the project. It include the cost of the objects, the cost of the installation, the tools and materials necessary to install it.

Next level of development is sustainability approach for the building. It includes accurate energy building performance analysis and its optimization, tracking the sustainable objects used in the project and LEED. Integrating BIM with 6D models leads to general reduction in energy consumption.

7D BIM level model is used by managers in the operation and maintenance of the facility throughout its life cycle. 

The seventh dimension of BIM allows participants to extract and track relevant asset data such as component status, specifications, maintenance/operation manuals, warranty datas etc. 7D BIM provides processes for managing subcontractor/supplier data and facility component through the entire facility life cycle. (taken from http://www.impararia.com/en/services/bim/bim-3d?id=244)

However I believe that 7D BIM isn't the last one, as technologies and people evolve there will be always something more.