The other model that works well is the open source one, with the maintainer having "another job"; e.g. academics doing scientific research (CERN!) or corporations who use the project internally. Unfortunately, the fact that the latter vastly outnumber the former means that the largest open-source projects are arguably corporate middleware or those of benefit to large corporations rather than users per se. People like me who use linux a lot are free software zealots. I wish Apple was more open on this -- they could quite easily be a hardware company and charge for services and yet make the code free -- but for whatever reason they've always kept the code close to their chest.

Subscriptions may make more sense as B2B software where the needs change over time, businesses tend to like having a two-way conversation more and a well-defined bill at the end of each year isn't necessarily a bad thing. As a private consumer though, selling a subscription is a surefire way to make me say no -- I'm not doing it.