He also said that they had the full 2.x (so up though 2.55) planned out by the time 2.1 released. Mentioning it in terms of 2.1 implies that they did not have that much planned when 2.0 initially released. So they were running around a year to a year and a half ahead in their planning at that point. That they're now planning out their 4.0 story when 3.0 isn't out yet means they're already shifting their lead time a bit further out.

(Of course, after the original FFXIV crashed and burned in more ways than one, they were rather under the gun to get 2.0 out. I suspect that involved enough time pressure during the lead up to ARR that they would have had to focus most of their attention on just 2.0 itself and likely couldn't get as detailed in their advance planning as they might have wanted to. So this is more like their lead time is recovering a bit after that. Of course, this part is pure speculation.)