I like unified developing environment for v5 in Themes and Apps. easy to work when it's come to adding basic functions and features and at the same time, open for extensive coding outside. basic functions and features like adding new language strings, settings, tabs, separators should be all handled smoothly inside the development area. manage settings in v4 Themes, is what i like to be implement for app/theme creation for v5... with more integrations and features.
One more thing is about implementing new measures to prevent piracy. personally have little knowledge about what already is done and how people can find ways to get around it, but it should be effective methods to prevent it.