Pick a subset of Debian that is the core. Release the core only when it's ready, which should be more frequently than when all of Debian is ready. For the other stuff, users would have to [FIXME: do what?]
- Shorter release cycles - don't have to wait for Gnome/KDE/insert-big-and-not-essential-package-of-choice-here.
- Package pool could theoretically be reduced to a few megabytes.
- Users are on their own with most of the applications, since Debian's archive is de-facto reduced to just another pool with almost no QA (3rd party pools can do the same).
- Security updates only for core packages, or the need for another security infrastructure (when and where to release security updates for non-core packages?).
Other thoughts: This could be combined with the ReleasePerSubsystem model, core would simply be a subsystem in this model.
This is basically what Ubuntu is doing. Ubuntu's main is a subset of Debian main. In addition, universe exists, which is the rest of Debian main. Universe does not receive security support or fixes. This works fairly well, but probably due to Debian fixing most serious problems in those packages.
See ReleaseProposals for alternatives.
As a user, I'd like to point out that one of the best things about Debian is that 99+% of the software I want is installable from the archive. Because of this, I can rely on it to play well with all the other software on my computer. Contrast the experience on distributions (e.g. Red Hat) where there is far less software in the official archive: one has to resort to 3rd-party package repositories all the time, and packages from those repositories frequently do not play well with each other or even the official packages.
I'd hate to see Debian develop such problems.
-- Zack Weinberg (happily tracking unstable since 1998)