Environmental preservationists... er, no, I won't try to make any fully general accusations about them. But if they succeed in preserving the environment in its current state, that would involve massive amounts of suffering, which would be bad!

Indeed. It may be rare among the LW community, but a number of people actually have a strong intuition that humans ought to preserve nature as it is, without interference, even if that means preserving suffering. As one example, Ned Hettinger wrote the following in his 1994 article, "Bambi Lovers versus Tree Huggers: A Critique of Rolston"s Environmental Ethics": "Respecting nature means respecting the ways in which nature trades values, and such respect includes painful killings for the purpose of life support."

Or, more accurately, our belief in utilitarianism is a fact about ourselves, not a fact about the universe.

Indeed. Like many others here, I subscribe to emotivism as well as utilitarianism.

Anyway, CEV is supposed to somehow take all of these details into account, and somehow generate an outcome that everyone will be satisfied with.

Yes, that's the ideal. But the planning fallacy tells us how much harder it is to make things work in practice than to imagine how they should work. Actually implementing CEV requires work, not magic, and that's precisely why we're having this conversation, as well as why SIAI's research is so important. :)

but I still suspect that if it really is such a good idea, then it should somehow be a part of the CEV extrapolation.

I hope so. Of course, it's not as though the only two possibilities are "CEV" or "extinction." There are lots of third possibilities for how the power politics of the future will play out (indeed, CEV seems exceedingly quixotic by comparison with many other political "realist" scenarios I can imagine), and having a broader base of memetic support is an important component of succeeding in those political battles. More wild-animal supporters also means more people with economic and intellectual clout.

I would hope that anyone who disagrees with utilitarianism, only disagrees because of an inconsistency in their value system, and that resolving this inconsistency would leave them with utilitarianism as their value system. But I'm estimating the probability that this is the case at... significantly less than 50%.

If you include paperclippers or suffering-maximizers in your definition of "anyone," then I'd put the probability close to 0%. If "anyone" just includes humans, I'd still put it less than, say, 10^-3.

Just so long as they don't force any other minds to experience pain.

Yeah, although if we take the perspective that individuals are different people over time (a "person" is just an observer-moment, not the entire set of observer-moments of an organism), then any choice at one instant for pain in another instant amounts to "forcing someone" to feel pain....