Thanks Julie for such a thought-provoking question - or series of questions really, your post is rich and covers a lot of important issues.
Looking at the present situation first, it's clear that the pattern of large-scale, high-input, low diversity cash cropping we see today is the product of centuries of social engineering, beginning with bringing land into private ownership (often replacing customary and traditional systems of land use that supported agroecological methods with much in common with permaculture farming) and continuing with fiscal, market and legislative structures that favour market specialisation and consolidation. Particularly important at the moment are subsidy structures - both the direct subsidies paid to farmers themselves (on which, in the UK at least, all large scale commercial farms depend), and indirect subsidies paid to, for example, the fossil fuel industries and large-scale retailers. Rafter Sass Ferguson's work on farms in the US shows that small-scale permaculture-based operations of the type you and I would like to see more of struggle to compete financially because of the way these structures favour the intensive model. Here in the UK, research conducted by the Ecological Land Cooperative shows that small-scale low impact farms using agroecological methods can - unlike most conventional farms - be financially viable without subsidies, as well as producing myriad other benefits (ecological, social, cultural, educational - not to mention mitigating and adapting to climate change). A big aim of the book is to communicate to people in policy, business and other areas that affect these wider contexts the benefits and value of permaculture and the many different approaches employed on permaculture farms. We also consider commons-based approaches to ownership of and decision-making over land and new approaches to business that are more consistent with the practical aspects of permaculture, as well as being versatile and flexible enough to cope with new circumstances like those we're seeing come about through climate change and other major social and ecological upheavals (like the financial turbulence Redhawk refers to in the next post). It's my view that major shifts in all these areas are necessary to help us adopt and work towards resilient and zero-carbon approaches to food production with the urgency demanded by climate change.
So while I think that what I've said so far will make it clear that I don't completely agree with your husband, I can see his point, in that we can't seek to impose change on others. What we can do as permaculturists is educate, inspire, facilitate dialogue, and lead by example in order to help emerge bioregional strategies that take into account, and seek to reconcile, the needs, interests and concerns of all people involved as well as seeking to do what's best for the land and its non-human inhabitants. So my answer to your husband's question would be that to permaculturise Palouse I would initiate comprehensive multi-stakeholder dialogue, and feed into that suitable information about the relationships between agriculture and climate change, the consequences, and possible solutions being applied in permaculture and many other fields. I'd bet the existing farming community would have a lot of vital knowledge, ideas and skills for such an undertaking. There's certainly general evidence for the benefits of downscaling, but whether a voluntary shift to small-scale agriculture is possible in any particular place - or whether large-scale farming can somehow transform to lower-input, more diverse, socially just and climate-friendly forms - to me are questions that are hard to answer by any other way than giving it a try.