The trick is to not make linear story-driven content as your primary content. Because while railroaded story-driven content is great for the narrative it's horrible for replayability and gets boring very quickly.
For example, imagine World Quests were available at level 100 as soon as you entered the Broken Isles. They could tell you the general theme and lore of a zone without putting you on railroads. Tell the main story with something like Class Campaigns instead that send you out into the world to explore, kill and retrieve certain stuff while doing other content (open world, dungeons, raids) unlocking further content.