I guess we shall see how blizzard approach it.
They want it to be an endgame pillar experience that you can solo. Which means if it’s endgame and not just a scaling world quest, it needs to strike that balance of proper time investment and appropriate gear ratio.
The rewards needs to be relevant enough to be worth doing. It sounds like with the example of a candle system granting light and the NPC companion, it will lead to a lot of trial and error which would inflate the time which would incentivize players more focused on other end game pillars to not go down the path of Delves since it’s not a quick knockout kill x or collect x things to get fast reward.
Again, we shall see how it all pans out.