If the project is economically viable, the private sector will get involved.
The problem we have with heritage preservation is there are always so many more needs for the private sector to be involved in, be it poverty, be it health care issues. The demand for funds for non-economic projects or charities, societies, is tremendously limited, because there are always other good causes.
The grassroots of support is there. There are a lot of people who will put in time and effort, but the economics typically aren't there because there are other demands on their funds.