One of the things that was mentioned at the panel, and that started to bother me about halfway through the book, was that, although the Condor failed in their war for reasons that were eventually explained and fit the world well, it seemed unlikely that some other culture wouldn't soon do a similar thing more successfully (or, as it was bothering me while I was reading, that some other culture hadn't done it already). This kind of broke me out of the book, which I'd been reading in a very predictive, this-could-come-to-pass way, and made it seem a lot less realistic.
But looking back on it, I realize that it's not a realism problem. It's a time problem.
The way the book is presented is also the way the Kesh see the world: everything is as it has always been and will always be. It's in the eternal present. But the actual bits of the book -- the poems, the plays, Stone Telling's story -- all come from a particular present. The way of life of the Kesh, although they think of it as eternal, may not last very long. The strong sense of place and home and cycles that's present in the book makes it feel like a culture that has lasted a long time and will last much longer, but their attitude toward history makes it impossible to know whether that's the case.
In retrospect, it feels like a precious soap bubble, a specific moment in time. The Kesh may be coming from or becoming some very different culture; the tanks may be just over the hill. But this isn't visible from inside the book, because the book is using the ethnographic present, which dovetails with the Kesh cyclic concepts to create this sense of timelessness, which is not necessarily reflected in the history of the Kesh or the world as an outside observer with a linear sense of time would record it.
I know I saw more hands raised than there was time to call on, so this seems like a good place to continue the panel discussion, if any of those people would like to add their comments.