For a period of time the NMEA 2000 AIS sentences were not approved by NMEA, but now that they are; I would expect Furuno to adopt it. I am sorry; I don't know when it might come around. It is still just one connection regardless if you are talking NMEA 2000, 0183, or network. If you wire up AIS to the NN3D MFD via 0183, it goes over the network to ALL units, so NMEA 2000 isn't offering a big advantage in this example.
Johnny