In terms of story, I mean. At the Elwynn Forest end, you had the small hint about the Collector's Ring and the Defias, which bleeds into Westfall's story. Redridge's story kinda bleeds into Burning Steppes with Keeshan and the Orc story. Felwood's furbolg stuff connects with Winterspring.
Do any Broken Isle zone endings actually give you that breadcrumb quest that says 'Go to this zone now' (Like the majority of zone quests), or can you just choose where to go?