The idea is to integrate the kickstarter model with github's issues (specifically, feature requests). You run an open-source project and people can submit feature requests that come with a fundraising campaign.
When someone wants the software to do something new (support a new platform, implement an interface, etc) they draft a campaign a la kickstarter, someone who can contribute to the project negotiates with the drafter pricing, targets, and stretch goals.
Past this point, it's the drafter's responsibility to do the marketing for the campaign and raise funds. Once the target $ amount is hit, it's on the person who picked up the contract to get the work done.
There are, of course, a ton of details to work out, and executing on this is going to be resource-intense on a number of vectors that aren't necessarily technical (legal, finance, hosting costs). Also, I suck at UI. The business itself would naturally be a non-profit.
addendum: I also have a day job that I have no intention of leaving, so factor that in to time-to-completion.