The D2C has been on a roughly two month update cycle up until this point so I would have expected a new firmware release in late October or early November.
However, given that the FW 4.00 for the D2 Delta series was so big (with lots of issues fixed), I suspect that the focus of late had been on the D2D and they are only now tackling the D2C firmware. I've sent an email to Garmin to see if I can get a rough idea of when the next D2C is expected.
It is sad that Garmin is taking so long to send out FW updates to the D2 series compared to the less expensive Fenix series watches. I understand that updates for the aviation features may take longer but they need to figure out a way send out non-aviation feature updates sooner.