About time: searching within apps. Google made preparations for that in KitKat, but now first results can be seen. Then, search on your phone will get a completely new and higher relevance: if you can find content based on keywords (or whatever) in apps and documents on your phone, the whole logic of app usage may change. And all these unused apps may become relevant again. Of course, there are issues - for exaple to exclude certain apps from phone search etc. But this could be something big for Android.