Personally I think nvidia is restraining the drivers, because they are in negotiations with Apple to provide the GPUs for the upcoming iMac and do not want to mess up the relationship with Apple. Another reason might be, that alternative drivers will not be necessary, because some future macOS Update will contain them (possibly because a new Mac have some Pascal-GPU).
It would be really sad, if Nvidia is dropping the alternative Mac-drivers, because it was the most easiest way to enable a gpu in a hackintosh (beside full out of the box support).