Thoughts on how my ideal mobile OS works:
* Server offload of heavy tasks (like web browsing) and any background tasks that can be offloaded (GPS navigation and music playback can't be, staying connected to IRC and IM services can be), with the server optionally under your control. (Think BlackBerry Enterprise Server plus Opera Mini.)
* Simple, lightweight native applications with consistent UI
* Task-oriented UI, rather than service-oriented. Skype, for example, should plug into the messaging and telephony clients, rather than be its own app. (Think webOS Synergy, BlackBerry Hub to an extent, Windows Phone 7 People Hub)
* Emphasis on extreme battery life. Let's say that, with 8 hours of active use per day, on two Energizer E91 or Duracell MN1500 AA batteries, with a mono non-backlit screen, on LTE, it should last 24 hours. (Don't actually use alkaline AAs, this is just an example!)
* Full support for non-touch interaction methods, including support for physical keyboards, but with touch being there as well
* As far as how much hardware performance this thing needs... it needs enough to run whatever camera it has, and it needs enough to play back at least 480p60 video smoothly, and ideally 1080p60 (downscaled to the panel, which should *NOT* be 1080p), without a notable decrease in performance.