"Anyone who wants to" is one model, perhaps with some goodies thrown in for those who do. A bunch of musicians have been using that in various forms for the past decade or so (e.g. http://www.neubauten.org/?q=supporters-english), and Kickstarter now sort of formalizes it.
I'm not convinced that that sort of model can support as much production, and thus we might see a lower level of production of information goods, but I suppose only the future will tell. Musicians always have the fallback of concerts, as I mentioned in another comment.
Blixa and Neubauten have a large and loyal fanbase from the decades they spent making music the 'old' way. Thus they (like NiN and Radiohead) can skip the hard "build a captive audience" step necessary for something like that to work. A new band no one has heard of is going to have a much harder time making something like that work, so as such it's not really comparable.
I agree it's not easy to pull off with no starting fan base, but isn't that true of breaking into the industry the old way too? An unknown band with no fan base is not going to have an easy time convincing an RIAA label to sign them and put out their album. I'm not sure their current problem (put out demos, find fans) is actually harder or lower-probability than the older problem was (put out demos, impress A/R person).
