Please tell me, what kind of DLCs you expect (or wish for) and I would like to know why you expect that.
I think, because of the ending it makes sense that most of these DLC's will take place apart from the commonwealth, like most of the previews Fallout DLCs
These I my guesses:
Simulation/memory pods: They are there and we haven't done anything cool with, so I am quite sure, that they will be part of an DLC. And they can be used for virtually anything. But I am not sure whether I want to return to an even better Alaska or do something rather strange like fighting against nightmares inside someone's head.
Synths army: I think Synths were rather passive the whole time and this whole morale dilemma would be explained more. Would be cool if synths did something on their own, like reprogramming other Synths in order to enslave humanity. Till now they were mostly props for the plot and enemies. And if you listen to Silver Shroud radio you can hear him fight the mechanist, might be a hint.
Something about the past of the Sole survivor: Kinda bothered me that my companions had more to say about the environment than the Sole Survivor, who lived there. Maybe he hears of descendants of former friends or family or maybe he is just searching for a McGuffin that belonged to him once.
Something on an island or an really large oil rig. Could be something rather linear like the Anchorage Campaign of Broken Steel.
Returning to the actual Alaska: That would be cool, but I am not sure if that makes sense. I mean it's would be a really long distance and it's not like you could simply book a flight. And think getting around during the Post-Apocalypse should be hard. But on the other hand, there were several people in Fallout 3, who made it from the commonwealth to DC, even though it makes me scratch my head when I think about.
There could be mechanics around not freezing to death.
Aliens: They are still there and the last time was pretty cool.