+1 custom content type UI and API,
+1 “use this theme for mobile devices (not a plugin)” – mobile is getting more and more important….and adding this as core would make sense.
+1 to – new default theme;
The permission system might also need a revamp…especially when publishing posts…you cant have several versions of a post…once you change it its automatically published..which might not make it suitable for enterprise use.
Show a more proper hierarchie in the pages section so you can extend and collapse the structure.