This may sound crazy, but I think the right model for open source funding is charging for updates. Developed world Ubuntu/Red Hat users should pay $20/year in updates, $5 of which goes to the distro, $5 which goes to the base system/core utilities, and the rest should fund your particular OSS apps/frameworks/support running above the base layer.

Yes, obviously donation/sponsorship doesn't work, but I'm not sure pay per issue resolved is the best model either. Good apps shouldn't be punished for having few issues, or needing few features.

People should be able to opt in, but I think opting in at the distro level is the right choice. Of course, there will be those that don't want to pay, but I think a premium model for power users and enterprise customers makes sense. These premium users could have access to beta/nightly channels, early SRPMS/src debs, and priority or triaged issue/PR resolution?