Well, looking at RoS, we see some shift towards tying some loose ends, now that Diablo is dead. While those area may be introduced in some form in the game, if an expansion is worked on, there is no point in having the whole act or acts there, unless they forced it in such form we need to accept it (I still haven't gotten over the Leah part of the story). And speaking about her, they always said they would like people to have a chance of finding her and releasing her spirit in some sense, so this may play a part. And if you go on this road, which is more important to the overall flow of the story of this game, then you have to tap in the Inarius/Lilith drama, and more specifically saving or destroying him in some capacity in the depths of hell, and in the chamber Mephisto tortured and imprisoned him. There is no point really of sidetracking the whole story to a irrelevant area where some people live shielded and oblivious to the core part of the story.
Again, they could do it, but then they have to force it, since there is no epic relevant reason to go there.
Oh, the lands of Askari (The Amazons). Wouldn't mind bouncing my boobs in Sanctuary again (but we already have a bow wielding class).
But on a serious note, and as the wiki states:
"Skovos was originally intended to appear in Diablo III, but was cut as it didn't seem to fit in."
"It was revealed during the 2008 BlizzCon's Lore & Art Panel for Diablo III that Skovos would not be visitable by the player during the events of the game, but was internally fleshed out so it could be made reference to by the people in the game world."
which means that the dialog between Tyrael and Lorath could be just another filler to the immersive experience.
Begs the questions:
Will Skovos have any more relevance now after the RoS expansion?, and
Who is leading them? Are they all corrupted in any shape or form? Are the pirates of The Twin Seas finally got a hold of the islands?
Tran Athulua, their prime town named after the prime deity of the Askari. Is the Sightless Eye to die for... still?
While a nice dive into the world of Sanctuary these lands are totally irrelevant unless The Eternal Conflict is at play to set Diablo's reign on helm. While is almost certain we will never see Diablo in this installment of the game, Adria made sure we get it through our thick skulls we will! He is the main antagonist of the world, and frankly the games will suck without him!