Free software is so important to society that I believe the most reasonable solution is to provide for all people without their need to work for survival. Automate as much as possible such that work is not compulsory, and enough people simply want something to do (and possibly additional pay depending on how the system is arranged) that everything that needs to get done by people does get done.

For now that is fiction, but so is "if all software was free". I do think though that both would lead to a faster rate of innovation in society versus one where critical information is withheld from society to pay someone's rent and food bills.