This is a complex topic, especially for open-source communities. The biggest problem is accountability and contracts, but that’s not an impossible task to tackle. Some open source projects were partly funded through crowdfunding and it worked well. Personnally, I would be glad to contribute to the development of SuperCollider by giving some money on a per-project, but not on a monthly basis.
There are a lot of universities and music institutions using SuperCollider almost everyday for some of their projects, as well as a substantial amount of musicians / teachers / artists / scientists. I think that many of us, and some of these institutions, would be willing to invest some money in funding SuperCollider’s development.
The problem is that doing such a thing and asking for crowdfunding would be a huge energy drain for quite some time, at least in the beginning: creating the right organisational structure, getting things right, convincing the community of devs and users, etc… I suppose that launching such an initiative would be very hard to do right, but could be done with a lot of determination/will/diplomacy, etc…
I hope that this topic will attract more people. It’s a nice topic to think / discuss about!