I don’t think PP are going away. A balance a little closer to EU4 would be well-received, though. Pretty much everything in Imperator takes Mana and there’s very little way a player can influence what they gain.
EU4 still derived from the monarch stats, but the can use a National Focus to focus on gaining one type. You could hire anywhere from +1 to +5 advisors in each category. Gaining 50 power projection gave you a bonus.
EU4 also allows you to do more outside of monarch points. You can fabricate claims and thus expand without them. You can work on diplomacy, fiddle with your trade network, establish colonies, all kinds of stuff. If you lack the MP in Imperator, you’re largely stuck.
I like the idea of abstract Mana, I think it makes for a good strategy game when deciding how to allocate a limited resource. Imperator likely pushed the needle too far, though, and some rebalancing would be good. For example, in the 1.1 update bribes cost gold from the character and not oratory power.