Just for reference, it took me approximately 78 hours to complete virtually everything in DAO, Awakening, and most of the smaller DLC. In DAO, we had really six major areas: Redcliffe, Tower of Magi, Orzammar, Dalish forest, Denerim, and Amaranthine. Each had a few major quest lines and the rest were smaller side missions. DAO wasn't a small game (it certainly was linear), but if you wanted to more or less complete everything, it did take a fair amount of time.
I'm expecting in order to achieve the same level of completeness, it will take substantially longer with DAI. Even with quick travel and trying to avoid long journeys on foot or by horse, regardless of all the large areas (much bigger than all of DAO), between just upgrading Skyhold, using the war table, and the overhaul of crafting, we have so many more and new activities that DAO just will not compare in terms of time.
In DAO, you were just focused on building an army and defeating the Archdemon. In DAI, there are so many tasks and responsibilities for the Inquisitor, especially adding all the aspects I described above, it's just an entirely different experience.