Endgame Suggestion for Sense of Continuing Adventure

So I haven't been that far into the endgame yet, just traveling across the map and fighting bosses. I like the concept of traveling across a map, to significant areas like citadels etc with bosses. It makes the game feel like the campaign is continuing.

ARPGs typically are known for a power grind and that is a huge portion of the fun, but it loses steam when you feel like you are done with the game. While the maps feel like I am still on an adventure, it still somewhat has a feel of do I need to keep going.

I feel that if in the beginning of maps maybe you were introduced to an NPC in one of the maps, who had a quest to complete across other maps it could bring a stronger feel of a continuing adventure. And possibly other NPCs who might randomly appear along with unique maps and events. For example, I might enter a map, but I randomly lucked out and the entire map was a different realm with an NPC and I would be curious about where I am and what event is happening. It would make me excited to travel to other maps to see what other random events might happen. Maybe some NPCs could become allies and some NPCs can become enemies and even bosses down the line.

That being said I did experience a unique event on an expedition where I had to detonate stones and thought it was cool but I think this concept could be further fleshed out with more significant NPCs, unique maps and events that would keep the player guessing and intrigued about whats around the next corner.