So to compile the information we already have on the issue.

1. It is widely believed from Square-Enix's wording that all characters made in 1.0 will have the "Legacy Story" that has a different opening without the carriage ride and just appear out of thin air and walks into town similar to the CG Derplander. You will also get a Legacy Mark and slightly different dialogues with NPCs at various points in the main story.

2. The way to tell whether your 1.0 got the "Legacy Story" is from the intro and Minfilia's dialogue. She will specifically apologize for having to act if she doesn't know you.

3. Whether you beat Nael seems to have no bearing on whether you get the "Legacy Story" or not. For example, Zeille and Keres above have not beaten Nael in 1.0 but still got the Legacy beginning.

4. We have no idea if Legacy status is required to get the "Legacy Story", however, there are players who DO have Legacy status, such as ravndark, who still got the new character story and not the "Legacy Story"

I'd also like to add that I'm a none-Legacy 1.0 player who only got as far as the quest where you attempt to settle the dispute between the crystal exchange company and the Ixian and Amal'jaa. I did NOT get the "Legacy Story" intro.