Two key impediments of sustainability are the dis-ease found in our social and cultural structures and intra and inter personal relationships.
We all have complex relationships within ourselves, between each other and with the environment. We can degrade these relationships thus producing dis-ease or improve them to produce health. To recognize this problem is a key step in that most of the focus is currently on our relationship with the environment.

Social and cultural structures and knowledge define personal emotional/psychological relationships and therefore health. There seems to be clear relationship between the dis-ease of our social/ cultural systems and the varying levels of personal emotional/ psychological dis-ease that is growing, and preventing sustainability from manifesting socially or environmentally. The basis and possibly penultimate periods of our lives being in-utero, infancy and childhood where the conditioning of negative experiences and treatment has life long lasting implications. People who do not receive beneficial experiences and conditioning will need to re-condition and relearn modes of healthy intra and inter personal relationships to gain real health which I believe includes most of us proof of  this seen in the levels of social problems nationally and the inability of most of us to live without destructive frequent conflict in compressed living arrangements such as intentional communities.
On the next level, sustainability comes down to using less and sharing more because personal space, personal transport, personal freedom and privacy are the most energy guzzling aspects of our society. Inter and intra personal dis-ease increases the difficulty of us being able to address achieve this.
No one alternative technology or group of technologies will be able to support us without seriously addressing the impediments of intra and inter personal dis-ease and the social structures that guide the flow of human energy in an unharmonious way where we are unable to HAPPILY use less and share more.