OSRIC is so far strictly in the hands of hobbyists, which is just where D&D started. Gary did not quit being a cobbler upon its publication, because he had a family to feed.
I think there are a few key differences.
First, remember Gary was an insurance agent. He became a cobbler to make ends meet for his family because he was investing his life and time into the game. By taking that act, Gary crossed over from a hobbyist to an entrepreneur. He DID quit his job.
People today forget the fact that TSR got as big as it did because of the investments of time, capital, and sweat. The fans alone did not grow D&D. They are a big part of it, but as they grew in size TSR had the capacity to find more ways to distribute the game to the masses--getting bookstore deals, finding better artists and production values and they got more money, etc. Gary (and some of the other early writers) also had a sort of charismatic thing going in his writing that affected fans. And it also hit a cultural zeitgeist that has yet to be repeated.
I don't believe the old school gaming movement, while being significant, is going to be very big. Even if it follows open source philosophy, it's already fractured. Technically, there are already half a dozen clones or variants of the core D&D/AD&D base. And the business factor is a big key to growing things--most of the arguments to put OSRIC in bookstores feel more like "religious advocacy" perspectives.
Right now I think the old school movement is rising because of two things--gamers who were teens or pre-teens during the rise of D&D reaching middle age, and the fact that WoTC really went a too radical with their new version of D&D. (I'm really surprised WoTC hasn't decided to go after this market--although whether they are qualified to do so is another question, a lot of the staff old-schoolers trust have scattered to the four winds).
