There is essentially nothing that stands in the way of this except the will to do it and a device to motivate it, as evidenced by Samsung's recent offerings (wh

There is essentially nothing that stands in the way of this except the will to do it and a device to motivate it, as evidenced by Samsung's recent offerings (which, presumably for expediency, is limited to their specially instrumented apps). The fundamental models of Android does not preclude running multiple activities at once, assuming you can "focus" the back button to a specific pane.