No fallback mode in GNOME 3.8
As announced by the release team two weeks ago, the fallback mode will be gone in GNOME 3.8. The decision was taken after some discussion on the mailing list back in June and in October, as well as some discussion during Boston Summit 2012. We also have a wiki page detailing the discussion arguments.
In my opinion, the biggest issue we had with the fallback mode is that, with only a few cycles, it quickly became clearly not tested enough, and lacked manpower for proper evolution along with other GNOME 3 changes. This resulted in a much lower quality than what we expect from GNOME. Moreover, several applications actually started requiring Clutter, and therefore didn't work anymore in a real fallback manner (ie, where you have no proper 3D acceleration); this means the fallback mode, when really used as a fallback, was not offering a fully usable desktop, and would be considered more like an alternative shell than a fallback mode.
Where does this leave us?, you might ask.
Well, for a start, GNOME 3.x had several iterative cycles to bring tons of improvements. Many users who were using the fallback mode because they didn't like the GNOME Shell experience are now happy with 3.6. But we're going an extra step starting with the next version: there is an explicit goal of having the project provide a set of extensions to help even more people preferring the fallback mode experience. The tentative list of what the extensions would provide is classic alt-tab, task bar, minimize/maximize buttons, and a main menu. This effort is being publicly tracked, so everyone can participate: if you're interested in contributing to these extensions, don't hesitate, I have no doubt help will be welcomed! Update: this topic is being discussed on desktop-devel-list right now!
There will also be work on improving GNOME 3 when running with software rendering. Of course, llvmpipe was a good start, and llvmpipe itself is getting better and better. But in addition, there are plans to offer a reduced resources mode, with fewer animations, that would be used in different circumstances, including when using software rendering. This should really improve the performances under llvmpipe.
There might be cases where these improvements will not be good enough in 3.8 (or with the Mesa and llvmpipe versions available at that time), resulting in a GNOME version that people might not consider acceptable in terms of performance or hardware support. Things will improve with time, obviously, and 3.10 will solve more and more issues; hence I would recommend to people hitting such issues to stay with 3.6 for a few more months.
All in all, the community is working on having future versions of GNOME, starting with GNOME 3.8, offer an improved alternative to the fallback mode.
Future of gnome-panel (and other fallback components)
Of course, this raises the question of what happens to the components of the fallback mode: gnome-applets, gnome-panel, gnome-screensaver, metacity, notification-daemon, polkit-gnome, etc. These components don't necessarily have to go away: they're just not part of what the GNOME project officially releases, and people are welcome to keep working on them. It's really up to each maintainer.
As for myself, I do not intend to keep maintaining gnome-panel after 3.6.x. I did a 3.6.2 release a few days ago, and it might well be what I consider my final release. If there's a strong push for some patches, there could be a 3.6.3 tarball... So, if you want to keep gnome-panel alive, contact me and you can become maintainer. As long as I either know you, or I can see that you have some minimal coding abilities, you'll get the maintainer hat for free :-)
Now, I believe a group of people could well adopt all the fallback components and keep building a great desktop, on top of other GNOME 3 bricks. They wouldn't even have to restrict themselves to what the GNOME 3 vision is (which is something that blocked some people from seriously contributing to gnome-panel). I don't think it'd be actually too much work: the code is already there! Of course, there would be some compatibility bits removed from other GNOME modules that would need to be moved elsewhere, but in most cases, it's really just about
moving the code, not
To be honest, I would really have loved if the MATE people had taken such an approach (maybe it's not too late?). I think it's a more reasonable effort than effectively forking all of GNOME 2, including obsolete technologies, as the amount of work is much more reasonable.
I'm eager to see if a group will step up to keep alive this old code, which represents thousands of hours from many of us! I wouldn't use it, but it would still make me happy :-)