In the end, this will all depend on everyone in the community, to not be moronic narcissists. People stealing content, ridiculous prices(which is understandable with Valve's greedy cut), etc. The whole thing about supporting mod authors is allready available through donations, but thats only support and not stable income. For stable income i think a sort of, mod request system would be the best way for everyone getting a chance, but copyright and conflicts and come from this as well. The biggest problem with this whole subject, is that Valve takes too much, and that needs to change. I personally will not pay for any mod on steam, whilst Valve takes more then 20 percent. I don't know this needs more research.