In other words, steepen the power curve. That's what 3e did, and it didn't work out so well other than at very low levels.
My take is that WotC needs to admit that D&D is not - and doesn't work as - a supers game, and come at design from a much more gritty and grounded angle
Not steepen the curve.
- Choose what you want to increase with level
- Choose what you DONT want to increase with level
- Have those first things increase just enough that every level something goes up that matters.
- And don't have any of those things stack with anything else.
Just to hit, AC, saving throws, and class DC increase.