I think that it will be quite difficult to make this possible exclusively from individuals. Unless there were a threat that the projects will stop, or an offer

I think that it will be quite difficult to make this possible exclusively from individuals. Unless there were a threat that the projects will stop, or an offer of doing more that's pretty clear, most don't have a strong incentive to give. Something like kick starter helps to solve this in a way tipping doesn't. What about a sponsorship component? Facilitating companies sponsoring a programmer? Their github page gets a logo or something, and they get a bit check each month. It's not a new model. Skateboarding, for example, which has no practical use aside from entertainment, often works this way I think. Many skaters earn their living from sponsorship and make next to nothing from competitions or whatever else. If there were a major github competitor (maybe there is, I'm not so much in a position to know), the rivals might also pay these figures to work on the projects they control on their platforms. It helps Github immensely to have all these projects on its platform.