What I would like to see Nissan do is provide a portable EVSE like Tesla's MC (Mobile Connector) EVSE, but which (of course) uses a J1772 connector instead of Tesla's proprietary one. This way the detachable input plug used would more safely determine the voltage and the maximum available EVSE charging current available to the EV, probably like the following:
NEMA 5-15r (typical 120v receptacle w/ "equipment ground") --> 12a, 120v;
NEMA 10-30r (older dryer receptacle w/o separate "equipment ground") --> 24a, 240v;
NEMA 14-30r (newer dryer receptacle w/ separate "equipment ground") --> 24a, 240v;
NEMA 14-50r (RV parks) --> 40a, 240v;
NEMA 6-50r (welding and EVSE outlets) --> 32a, 240v (note: often used for "50a" circuits, but can only rely on "40a" rating)
Like Tesla has decided for its Model S, I think Nissan should NOT include a 16a NEMA 5-20r adapter because the receptacle cannot (unfortunately) be relied upon to safely indicate its true circuit rating (because of widespread receptacle misuse).
One problem with this is its value would make it a target for thieves.