Well obviously they can't program more range in there if there isn't enough battery capacity to support it, but if there is that typical 10% unused margin, they could dip into that if they wanted. Reminds me of a lawsuit that was attempted against Apple for showing the battery being charged to 100% even though it was only charged to 90% in actuality, in order to prevent battery degradation. They added in that extra 10% capacity in order to improve the long term life of the batteries. Tesla does the same, and of course Nissan as well.
It reminds me of the debacle in the late 90's regarding CRT size. TVs advertised as 27" really only had 25" displayable, so shortly before they were made obsolete by LCD screens, they started having to have a sub-script under the main tube size as to what the displayable size was..
Pulled the trigger on going EV on 10/2016 with a 2012 Leaf, and a Tesla Model 3 reservation expected to receive in late 2018.