The fallback mode, also known as the classic GNOME session, will no longer be included starting with GNOME 3.8, the next stable GNOME release. Users running computers without graphical acceleration can use GNOME Shell through llvmpipe, which is already supported for some releases.
I'm writing to inform you that the release team discussed ["Drop or Fix Fallback Mode"] yesterday. We've come to the conclusion that we can't maintain fallback mode in reasonable quality, and are better off dropping it.
The GNOME 3.8 features page mentions some of the reasons behind the decision to drop the fallback mode of which, the most important one seems that "it's in maintenance mode", without no new features or active development for a long time. Other reasons include:
- nearly nobody actively tests it
- the presence of fallback mode is having a negative impact on the quality of the primary GNOME 3 user experience
- several apps such as Totem or Cheese now require Clutter and can't work without GL. Thus they won't work in fallback mode
- some changes in the architecture require additional work to keep things somewhat working in fallback, even though they won't offer the full experience
Dropping the follback mode doesn't just mean there will be no more classic GNOME session. With it, some GNOME modules might go away, like Metacity, GNOME Panel, GNOME Applets, notification-daemon, GNOME Screensaver, polkit-gnome and nm-applet. Furthermore, this decision affects Unity, LXDE or Xfce too because they make use of some fallback components like tray icons of GNOME Settings Daemon.
But not all is bad, because dropping the fallback mode means that some modules like GNOME Control Center, GDM or Nautilus could be simplified, mentions the "Drop or Fix Fallback Mode" page.
The GNOME developers didn't forget about the users who prefer a GNOME 2-like layout, and it looks like they will compile and maybe help maintain a list of GNOME Shell extensions that provide such a layout.
Ubuntu users don't have to worry about this just yet, since the next Ubuntu version - 13.04 Raring Ringtail -, will continue to use GNOME 3.6 for the most part and not the latest GNOME 3.8 which will ship without the fallback mode.