We have eternal and seasonal realms, but what about realms that make major changes to the pace and style of the game, but only in easily scriptable ways to make it feasible.
One thing that all realms can benefit from would be additional torment levels where the campaigns can be replayed and side quests reset once enough of them have been done, with reward caches at these levels having a obducite, gems, ancestrals, and fair chances for mythics and legendary runes. Basically these storytelling bits of gameplay that can serve as an alternative to the grind that we call an endgame.
But in the new story casual/roleplay realm, horde compasses, artificers stones, and nmd sigils would be a rare reward for side and story quests and world events.
The idea closer to d2 but with a lot more content. Work through t1 to get stuff to do it in t2 etc with mentioned rewards for when you gotta do something different.
Some damage scaling of abilities would be much more aggressive at the lower end and with diminishing returns at the high end to compress it so that content can be balanced around more builds and styles rather than the flavors of the month.
The game stays more challenging, more regularly rewarding, and content fresh with less direct repetition.
Pipe dream but its mine.