Good news is that you can use one of our flashed Kepler, Maxwell, or Pascal cards to run the High Sierra FIrmware Update. The Kepler cards will work fine in High Sierra already, with likely exception of Titan Black and 780Ti.
Initial testing with Pascal cards in High Sierra shows some changes. Anyone using The late Kepler cards mentioned above or Maxwell or Pascal cards should wait for Nvidia to release their Web Drivers.
More details soon. Anyone who has done some testing should feel free to post here.