I can think of alot of good that could come both for player and blizzard, if we had a set amount of resplendent sparks, (4) that carried over from season to season, instead of all going to eternal.
It would make all that grinding worth it to start your season in something comfortable at level 35.
Then on the flip side, that means a prolonged increase in player count until the goal is achieved.
I know people who spend all season grinding 4 new characters to get one uber, so something like this would make them WANT to grind twice.
I would tie it to a quest to unlock the ability to carry over 4. (i have already written out the quest script) It needs to be done every season.
Its just a thought. Im sure plenty of you hate that idea, but for QOL, not sure it gets much better, especially with what just happened to your ubers. I dont think that is to op seeings as how you must invest the time and effort season prior to achieve it.