There is another potential source of funding for open source that is quite congruent to its ethos and that is the public sector. For many types of software used by public sector entities it would be quite efficient to support open source development as a public good.
There will always be points of view that would consider this (too) as a problematic source of funding (e.g., being suspicious of government actors and their motives) and it can be a major hassle to handle public sector bureaucracy, but given the distribution of demand for software in the economy it seems something natural to some extend and it could alleviate some of the sustainability issues with open source development.
There will always be points of view that would consider this (too) as a problematic source of funding (e.g., being suspicious of government actors and their motives) and it can be a major hassle to handle public sector bureaucracy, but given the distribution of demand for software in the economy it seems something natural to some extend and it could alleviate some of the sustainability issues with open source development.