Apple has applied for a patent on a combination SD/USB port which could be used to save space on the ever-shrinking MacBook Pro and Air. This would allow more ports to be added to a system. The patent offers USB and SD cards as the example, but it could easily be applied to other connectors.
Apple explains it in technical speak:
The input port includes an outer wall defining a receiving aperture, a substrate positioned within the receiving aperture. A first set of contacts is positioned on the substrate at a first depth into the receiving aperture and a second set of contacts is positioned on a first surface of the outer wall at a second depth into the receiving aperture. The first set of contacts is configured to communicate with a first connector and the second set of contacts is configured to communicate with a second connector.
Whether or not something like this would come to fruition depends on if Apple can develop the technology behind combining ports. It's a rather difficult problem due to different form-factors, connections, and other factors.