Why is Unity 2D being discontinued?

As reported by Phoronix, the news from UDS appears to be that development on Unity 2D will stop, with the focus being on a single, unified implementation.

Obviously maintaining two codebases to do the same thing is not ideal. However, Unity 2D was created for a reason ("Unity 2D's goal is to provide the Unity desktop shell on hardware platforms that cannot currently support Unity's OpenGL requirements"). Why is it no longer felt Unity 2D is needed?

Solution 1:

Unity 2D was conceived as a fallback mode for computers without the graphics hardware or drivers to run Unity properly. The project uses, as you say, a separate codebase, and has sucked up substantial engineering resources to stay consistent with the main interface.

Luckily, engineers at the Fedora project have successfully developed and integrated a technology for running rich, composited graphical environments on older hardware. Ubuntu can also adopt this solution. As such, Unity 2D as a fallback mode is now superfluous.

Everyone can now enjoy Unity, without the costs of developing a fallback alternative.

Here are the notes:

• http://summit.ubuntu.com/uds-q/meeting/20425/desktop-q-gnome-plans-review/