I'd love to see the various management consoles in Windows get streamlined into one, and feature a Ribbon. The Windows 95 look on these are quite awful to deal with anymore.
This! They already have the Microsoft Management Console as the base for everything. Now just to slap everything together in a cohesive way and make management easier.
There really is no need for a separate Device Manager, Disk Management, and GUIs when the same things are accessible through the Computer Management GUI which itself is an extension to the MMC. Even the Hyper-V management GUI is again an extension to the MMC. Surely these things can be unified in a good way into a single GUI?
EDIT: Another step that should be taken in the future, unify the exposed configurations in the old Control Panel and the new one. Everything that is accessible in the first should be accessible in the second, and vice versa. While they're at it, they should fix the old Control Panel to have a consistent feature exposure, as some things are not available in all view modes.