How do you unpack "fail" or "flounder" in this context? What counts as success?

If your criterion for success is "taking a group of people through the entire text without most of them dropping out" then yes, I also expect failure, but I wouldn't be bothered by it much.

Here relative success seems more important. On a personal level this is an opportnunity for me to get more out of Jaynes, through comparing notes with others, than I would otherwise have. Symmetrically others should get the same benefit. Some people will invest time in studying the book that they may not otherwise have, and depending on their goal just that may count as a success.

I've had a very satisfactory prior experience participating in an online SICP study group (i.e. I learned quite a bit about programming), and I was peripherally involved in a brown bag club that tackled Jerry Weinberg's Quality Software Management, the people who did stick with it got a lot out of it.