Yeah it is free for now, there are no guarantees about the future (death and taxes excepted and then I am not even sure about death), but why would you make that comment? The MOOCs don't owe you anything, they are providing the equivalent of a university degree for no cost, so why so negative?

I think there are conflicting incentives, and we've seen how these things tend to play out. It's really the universities and the professors teaching the classes who are providing the courses, and they need to be careful that they don't inadvertently put all this material into a walled garden under the assumption that they're giving it away to the world.

So far, there's no wall. There's just a gardener that can sell you a certificate that you indeed visited the garden, but you can still visit it anytime whether you pay or not.

And then all of the universities submitting courses to coursera would stop...