Granted, Dr. Fate met Nergal only once in the Golden Age. However, he was the first enemy that Kent V. Nelson went up against when he took over the role as Dr. Fate, and Nergal referenced the one time meeting from the Golden Age.
I hope this means that the possible Dr. Fate will be Kent V. Nelson. As it appears that the Helm does not have a host at this time, it may be entirely possible that the grandnephew of the original Kent Nelson might be the show's Dr. Fate. Of course if this happens I will be in comic fandom heaven.