Kurotowa
Legend
I don't believe any RPG should dominate the market and the cultural consciousness of the hobby as much as D&D does.
There will always be a dominant player in the field, because the Network Effect is a real thing. A market leader's value goes up the more people are plugged into the same shared network; it means everyone is linked together and not having to learn six different system at once. It's the same reason Facebook and Reddit dominate their fields as well. If D&D were to magically vanish tomorrow then it just turns into a scrum to see who the new predominant RPG is.