In general, GNOME needs to restore user confidence on a technical level. KDE has shown a willingness to rethink its innovations, rearranging its System Setup with every release, and continually experimenting with new displays in the hopes of making activities better known and more accessible.
In the same way, GNOME developers need to explore the possibility of compromising between their vision of GNOME 3 and what users demand. Desktop icons and panel icons alone would go a long way towards pacifying users whose workflow is different from the one assume in GNOME 3, because they would allow those who prefer a single screen to multiple desktops to work the way they prefer.
If developers get such compromises wrong the first time, they also need to revisit their solutions until they get them right.
Many of these possible lessons are not about coding. They are about reforming the existing culture of GNOME, discarding outdated and non-functional interactions in the same way that the latest release discards unnecessary code.
Such an effort will not be easy. If nothing else, it requires a self-reflection and a skill in long-term planning that the GNOME project has yet to demonstrate, and that may be foreign to its culture. Yet, even if the effort is only partly successful, KDE's example shows that it could go a long way towards restoring GNOME's credibility. Few users demand perfection so much as a sign that real efforts are being made to listen to them.
In all of this, the largest question is whether GNOME has the collective will to do what's necessary. The features list for the 3.1 and 3.2 release suggest that the issues are not being addressed, although perhaps they only mean that it will take a couple of releases before change can be scheduled or reflected in the code.
I hope that GNOME can do what is necessary. I really do. Seeing GNOME divided between Unity and GNOME-Shell, and reading the daily announcements of one user after another migrating to other desktops is like watching a car being hit by a train at a railroad crossing and being unable to do anything.
So far, however, the possibility of change doesn't seem likely -- even though the KDE recovery could tell GNOME members much of how they need to act.