Google surprised the tech community when they released the Android N Developer Preview a couple months before Google I/O, their annual developer conference. Among quite a few new features was split-screen multitasking.
Much of what we know about Android N has come from reading the documentation. After all, the only features that they told us about are the ones that they want us to know about before their big event.
As it turns out, there's more to this split-screen multitasking than we had imagined. The documentation for Android N discusses a freeform mode, which would include windowed apps.
It's not clear if the new freeform mode will come to just tablets or if it will support phones as well. After all, it was surprising to see Google decide to support split-screen on phones, since both Windows and iOS reserve that feature for tablets and in Windows' case, PCs.
Google could also be grooming a competitor to Microsoft's Continuum. It would be no surprise that Google wants to compete in the "phone that you can use as your desktop" market, after being left flat-footed in the "tablet that can replace your laptop" market.
If that's the case, then "freeform" and split-screen make perfect sense on phones. Of course, we won't know anything for sure until Google takes the stage at Google I/O.