Some of the recent announcement by Ubuntu clearly mentioned that their latest release 13.10 will replace X-window server (X.org) with their own Mir-Display Manager.
I strongly feel this is going to make a big impact in the Linux Community/Developers. Even-though the license is GPL, I think they are planning to reach the Eco-system that Android and Apple is having.
In some of the blog entires Ubuntu has mentioned that Unity 7 will run atop of XMir, an implementation of X that provides a compatibility layer that allows software, desktop environments, peripherals and multi-monitor setups designed for X to continue to work as expected.
But am not sure about how feasible it is .Looking forward to hear your inputs.
About Mir -
PS: Kubuntu has announced that they are not planing to switch to Mir. Below the comments made by Jonathan Riddell of Kubunut-
"A few months ago Canonical announced their new graphics system for Ubuntu, Mir. It's a shame the Linux desktop market hasn't taken off as we all hoped at the turn of the millennium and they feel the need to follow a more Apple or Android style of approach making an OS which works in isolation rather than as part of a community development method. Here at Kubuntu we still want to work as part of the community development, taking the fine software from KDE and other upstream projects and putting it on computers worldwide. So when Ubuntu desktop gets switched to Mir we won't be following. We'll be staying with X on the images for our 13.10 release now in development and the 14.04 LTS release next year. After that we hope to switch to Wayland which is what KDE and every other Linux distro hopes to do."