I expect they bring better graphics and I hope they bring better CPU performance, but really, for this to be an actual successor to Cities Skylines it needs to fix the nonsense the first game had, like all cities needed to be built upon an USA-like zoning system, the area of effect of infrastructure buildings like hospitals and police dpt were absurdly, unrealiscally low, the noise pollution system frequently simply didn't make sense, etc.
Basically giving player more freedom, maybe with selectable different sets of rules so the game would still be challenging while allowing for more diverse city arrangements.