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?]

Pros:

Cons:

Other thoughts: This could be combinated 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.