I think FFXIV attracts a different audience from games like D3. Honestly FFXIV's strength will be as a console MMO. Further its story-heavy while D3 is more about grinding than it is about in depth stories.

I think Star Wars will be its main testing ground. Its similar to FF as it is a story-heavy mmo, and it seems to be better in almost all aspects. If FFXIV is still successful after that i think it will be fine.