If there is sufficient in-world reason, I'll take it. I don't NEED Skyhold, I just don't understand why it seems to NOT be there.
Here's some ideas:
-Skyhold notes include a lot of 'we can't work on X because Skyhold was shaken by something and/or it is built on something else', akin to Temple of Sacred Ashes seemingly being on top of a Temple of Mythal or somesuch. If so, we could visit the site of Skyhold, but it'll be revealed to really 'be' something else.
-Skyhold could be in scenes but not directly visited.
-The library could be used in a future patch feature. While Trespasser may be the final SP DLC, they did NOT say whether the upcoming patch (Golden Nug + Wardrobe) will be the final PATCH. There can still be something that increases our attachment to DAI while waiting for the next game, and its clear now that Bioware is interested in us exploring as much as we can with some ease, given the Golden Nug news. We'll see, but I really hope that room means something aside from having some random and one (What is Green?) intriguing codex entry.
-Skyhold can still be assaulted but we just don't play a part in its defense. Plot stuff. Story can still hypothetically happen without us running around it like a main quest area. In Awakening, we don't exactly rush up to defend both Vigil's Keep and Amaranthine at the same time, but still surely still happens.
So I'm open to possibilities. My only real hope is that they don't sidestep Skyhold entirely. Maybe there would be great internal development reasons for that (not ones I'd like, but ones I'd comprehend), but it doesn't make sense to me from any narrative standpoint. We built this place up. We have it as our home. Even Haven, when torn down, had a level showing its tearing down. Losing Skyhold, either directly (conquest) or indirectly (not using it as base) should make sense, not just have the story go 'lalala' about. I'm not sure I'd accept a flimsy excuse either.
I see potential and just hope that Bioware acts on this potential instead of going "Yeah we decided not to do that because it was too much, so use the Winter Palace instead and forget about Skyhold."
Looking forward to LadyInsanity's interview.