> The general idea of creating overlays for actions that take awhile to complete should really be integrated into the system itself.
This was the feature of Android that got me really excited when Google first announced it. The whole idea of Intents is that you can have a stack of things you're doing; clicking a link will open a new Activity on the top of the stack and hitting Back will pop that Activity off the stack.
As Android was originally pitched, Applications shouldn't be the fundamental unit of navigating through your phone because you don't usually think in terms of "and now I want to open Chrome", but in terms of "I would now like to open this link". If you're reading an sms and click a link your buddy sent you, then from that webpage click another link that opens twitter you've found yourself in a "Task" with three separate Activities in it. You can then context switch to a different task and eventually back to this one with all your Activities waiting right where you left them.
But it seems Google has given up on that vision. Developers were given too much control over tasks and the "back stack" and too little education on thinking with Activities so they happily went along and tried to make monolithic applications. Like web browsers which tie all your tasks together into one app that has a bunch of tabs. What does the back button in Chrome do? Nobody ever knows. The back button in Chrome conflates your tab history with your Task history and makes them interact in convoluted ways. If it didn't expose tabs open in other tasks and treated every forward navigation like creating a new tab the Back button would be perfectly intuitive.
I mainly blame Google for never making your back stack explicit. To this day it's difficult to tell where the Back button will send you because Android never shows you (Also because some apps try to get smart and rewrite history at terribly inappropriate times, have I mentioned I hate Chrome?). The app switcher shouldn't be a list of the last Applications you've used but a list of your last few Tasks.
So, I don't agree that overlays should be part of Android 5. I think that the App Switcher should be given some real teeth, Intents should be overhauled, and all the default apps should rewritten to show developers how to think using Tasks.