I mean the first two forms were not race based because they were different versions of Ursoc and Ashamane's design with the pvp version being their Nightmare design and another version being a spirit form. They very much had two unique form in the end (stone bear and jalgar, owlcat and tiger) the rest just being variations on a theme. Meanwhile each new race, even allied race, that got access to druids, came with their own unique forms. I'd say the precedent then is the latter; unique racial forms. Imo I would really hope if Blizzard does Druid for all races they do it a bit more slowly than they did with other classes and actually add some minimal lore with each addition.