Great post. I would say I think the text storytelling phenomena has a lot closer analogy to blogging or podcasting than to social gaming. One of the issues of social gaming was the cost of entry kept going up, similar to traditional games. In the beginning, as we both know, you could stand a game up in 6 weeks that consumer would engage in —which let you rapidly iterate and test ideas. But the expectations on graphics and depth increased quickly so suddenly top social games where in development for 3 months, then 6, then 9, etc etc. and that changed a lot about how games were built.
Making a text story is unlikely to follow that curve. Cost of creation is low, as you mention, and it’s also important that cost of creation is likely to stay accessible even as competition heats up. That means amateurs get to stay involved in the creation process longer, which is excellent for creators and for the innovation likely to happen in the medium.