Assuming Heavensward goes like A Realm Reborn did yeah, after 3.4 we've got 3.5 and possibly 3.55 to go 'till 4.0. Where the story was going didn't start getting hints until very late 2.3, with 2.4 and 2.5 setting it up in earnest - since we've been dealing with the Dragonsong War for the entirety of 3.x, it looks like they skipped that tiny bit of setup in 3.3 for resolving the arc that started in 2.3. 3.4 is, from what we've seen, obviously going to start setting up 4.0.
... which is totally in development, by the way. It's ahead of schedule from what I heard (they're already recording voices for it). They just haven't put out any information yet, like where the story is going, what jobs are going to be added, if there's going to be a new race, etc.