Several sites have pointed to a tidbit of information that was part of a recent review of the Canon Eos-M 3 from DpReview:
Its closest peers, based on price and features, are the Fujifilm X-A2, Olympus E-M10 II and Sony a6000 (we’re leaving Nikon 1 cameras out of the list, as we believe the series is no longer being developed.)
DpReview is not known for publishing rumours, so I suspect that they know something that we don't know, especially given that their parent company is Amazon. If this is true it's a shame, but not that surprising. While I believe the Nikon 1 system has a degree of popularity in Aisa, I don't think it ever really took off outside of that region. Nikon's efforts in this area seem to have been half hearted at best. While they have released several cameras in the range over the years, they never really developed the lens system for the series.
Some are suggesting that this may signal a move from Nikon towards its long rumoured Full Frame mirrorless camera. This may well be the case, but in my opinion, this probably isn't the reason for Nikon killing the 1 system, if it is indeed killing it. In my view, it's the new, and much delayed Nikon DL series of premium compacts that may be the driving force behind a potential decision.
They use a similar 1 inch sensor, and Nikon may well have come to the conclusion, that this form factor better suits the sensor size than an interchangeable lens system. Given Sony's success with 1" cameras, it's not beyond the realms of possibility, that Nikon executives may feel that this is a better approach. Of course, that won't be of any comfort to any existing Nikon 1 owners.
It's worth re-emphasising that this is all just conjecture based on a single seemingly off the cuff comment in a DpReview article, so it may well amount to nothing. Yet, anyone who I've talked to about this hasn't seemed very surprised by the possibility. I still think it would be a shame though. While it may not have a huge following, the people who do use the Nikon 1 system seem to love it.