While the cladding and swirling camouflage make specific details difficult to discern, it doesn't look like we should expect any massive changes in design language from the new model. The nose appears to dip a bit more at the tip of the front end, but otherwise there's no way to mistake this as anything other than a 5 Series. Squint hard enough at the front left fender and you can notice what seems to be a small door. Our spies think that this might be hiding the charging port for a plug-in hybrid version.
While the styling doesn't appear to be changing much, the next 5er reportedly has a new platform underneath the skin that supposedly will help it shed around 220 pounds. The debut for this lighter but likely similar looking BMW is expected sometime in 2016.