You know- when you name the title of a DLC "Dragonborn" it makes me think that this DLC is Dovahkiin's "Swan Song." So, what's paramount for someone who is Dragonborn?
It does sound pretty final to me as well. Not that you will die, per-se... but more that this sounds like it was intended as the final expansion.
Especially when you consider it was only these three expansions (Dawnguard, Hearthfire and Dragonborn) that were copywrited at the same time.
...now, maybe, they might've underestimated Skyrim's popularity and if the sales of Dragonborn are good enough they may add new ones... but I am getting a bit of a "finale" feel for this one.