I see this kickstarter model as similar to large companies that contribute employee time to work on open source projects - this just decentralizes it, focuses the development more on the project, and establishes community demand prior to rolling out the feature.
If this continues do you risk drying up other non-compensated commits or risk contributors waiting for funding before pushing code? You might see a small decrease, but I'd be willing to bet the same dynamics that have kept the open source community moving forward will continue - you just might see more targeted, rapid progress in areas people are willing to fund and a small cottage industry emerge that makes money contributing to projects.
If this continues do you risk drying up other non-compensated commits or risk contributors waiting for funding before pushing code? You might see a small decrease, but I'd be willing to bet the same dynamics that have kept the open source community moving forward will continue - you just might see more targeted, rapid progress in areas people are willing to fund and a small cottage industry emerge that makes money contributing to projects.