This is just a short one, despite the grandiose title.
One of the things about a) Peak Oil (therefore Peak energy) and b) Global Warming, is that the energy structure of the future will necessarily be more diffuse and multiform (and more efficient and lower in carbon). There probably will still be a 'grid' of sorts, but it won't dominate electricity supply in the way it does now. The pattern will have much more resemblance to the internet, especially the 'Napster' model, with many nodes sharing product and lots of redundancy built in. The local will be the dominant factor. (And I remain convinced that the future is wired - what will Google do? etc)
I'm reminded to say this by this article, and the concept of systempunkt. In other words, as well as the pressures on the system coming from Peak Oil and Global Warming, we can add Global Guerrillas as another major force dictating the same outcome.
Fortunately, this outcome is deeply attractive and human.