The key innovation in Windows Phone's "Continuum" feature is that the desktop is just another view into the phone. You can access the same exact apps and user data - browser, mail, calendar, messaging, etc. - and switch back and forth without losing state. In that world, a phone with KVM support doesn't just save you from owning a PC; it saves you from having to keep track of a different set of installed apps, setting up accounts, preferences, and state (currently open tabs, documents, etc.)

I'd welcome something like that for Android, especially as Google is experimenting with support for windowed Android apps with mouse support.

Unfortunately, Maru is not that. It appears to only run X11 apps on the desktop, and only Android apps on the phone. I don't think there's enough value in that. It has the inconveniences of needing to dock/undock your phone plus all of the hassle of having to maintain 2 separate sets of apps, settings, and state.