It seems like the EVSE could know quite a bit more than that, Gary. It could know how much current the car is pulling, and how long it has been pulling that, and if that draw has remained constant since it was connected, or if it has tapered off, and how long it has been since it dropped to a lower level or, if it is dropping continuously, how long it will be until it drops to zero. Those could provide some pretty good hints as to when it would be available again.
But Nissan's system isn't going to be running the EVSE, is it? At least I would hope that we could get information about charging points no matter who is running them. This implies some sort of centralized data exchange accessible from each manufacturer's system. So at least in an ideal world, an EVSE might report in:
"Hello, I am a level 2 EVSE at geo-coordinates xxx,yyy and was just plugged in at 14:21:36."
Meanwhile, a car could report in:
"Hello, I am a Nissan Leaf at geo-coordinates xxx,yyy and was just plugged in at 14:21:36. My current battery state of charge is down 7.8kWh with a predicted time of 3.05 hours to recharge completely."
Now how much information could you get, at least in theory, about when a charging station is likely to be available?