The long-awaited change for the Quick Cast interface is going to be released in the next patch! Finally, you will be able to choose the settings for each ability! For example, you will be able to play Kerrigan with Quick Cast enabled and, at the same time, play another hero with Quick Cast disabled or set to On Release option.
Apart from the Per Ability Quick Cast setting and tease of new Illidan's icons, the developers are going to allow you bounding desired hotkeys to your mouse. Lastly, the Hots development team is going to improve the profile sharing of the hotkey interface.